Bhai log, this veda business are the birth pangs for the OIT. So my suggestion is, do not give up, instead all involved should proceed based on a humility that is human not on a sense of entitlement that is superhuman. Caveat is I am known for honest but crazy advice. I give it believing it is priceless, but since the price was paid by me only so your prerogative to treat it as worthless remains with you. To continue, basically OIT needs to treat this as the first challenge. Rest would be a downhill drive

(no sarcasm here).
Believe me OIT supporters would not like it if Vedics give their testimony
after the OIT is fully formed.
I do not expect responses, rather I request only a cursory read. Had you guys not started this ‘fight club with no blood in it’, I would have remained content reading you guys.
JMT vvv
The reason why Vedic Practioners (Practicing Brahmins) do not develop the whole philosophy around Veda itself could be because they are so involved in maintaining the purity of the original sound that it leave them with little time to do any of the exciting stuff. Looking at it the other way that itself is pretty exciting work. Almost like a 24X7 competition with oneself. I wish I had the kind of real time self control that a Vedic practice is supposed to produce.
AFAIU, Vedas are a grammatical arrangement of basically original sounds.
The easy part first:
Original as in, an effort to reproduce these words can easily meet their end in either a lazy tongue or an over active tougue. A kind of prime number of the sonic world producible or reproducible in a very limited manner. ‘A kind’ because there are more prime numbers then one can care for but seems like the ‘old man in a hurry’ got us all the original sounds leaving only the original combinations to us now.
Now the prime number is prime at only one point. Any operation on a prime takes way its primeness (divide it first &/or then multiply it or vice versa or WTH). I am not good at maths but making an effort to reach out to technical minded people.
The fly in the ointment is that life does not stay still. As a result what is prime/exclusive is only a qualified and ephemeral existence. I will have to qualify the primeness by saying something to the effect, 'all things remaining static', which seems rather unreasonable.
OTOH if we take life to be a moving-grooving dynamic experience then we would need something that explains everything by way of an inclusion/acknowledgment of past even if without accounting for every past. That is to say, a practice designed for a complete experience of the perfection of every moment instead of the primeness/uniqueness of only one moment. In the sonic world that could be Yagya and Vedic uchaaran. A practice designed to take one from realization of one perfect point to another without a seam in between and then keep up this process for good. The fact that a normal life is possible (a pretty rewarding one) without the intervention of Vedas is well recognized. But that does not imply that every practice of anything is designed to do what Vedic practice is supposed to do. Vedas retain their originality or first mover advantage on this count.
Moving further ahead, given such a situation, those interested in Vedas may actually not be interested or even have the resources for other pursuits.
However being Vedic does not imply a disinterest in dharma and to that extent Vedic practioners would be scathing on AIT which is unique in its obscurantist behaviour. But if OIT based on Vedas (henceforth 'Vedic-OIT') comes out as merely one more challenge to Vedic practice that too will be opposed by Vedic practioners because practice is what the Vedas are about in the first place. OIT is all about non-aithaasic history. To that extent there is danger for Vedic-OIT. The Vedic-OIT challenge is however neither unique nor of the same scale as AIT. This should attenuate the Practioners charge (witness the giving up by KLP Dubey ji).
Again Vedic practioner letting up the charge would still not be good for the health of Vedic-OIT as AIT Nazis have a greater lung power than SDRE OIT-walas. The first thing that a AIT Nazi is going to do is pit the Vedic-OIT against Vedic Practioners. That would not be good for anybody except the AIT Nazi.
Also one thing that baffles me is how can Vedic studies affirm OIT if it is used to invalidate AIT, by reason of the variable import of the sounds used. If it is variable, well tough luck, it becomes unusable for everybody involved. In this respect I do not see Vedic practioners as competitors to OIT. Rather a ‘constraint’ would be a more appropriate word. A valid one as I see it, but then that is only me.
The difficult part :
What is the grammar used?
Well no idea here boss. Ergo food for thought. Others before me raised this question in their own manner and tried to answer it too in their own manner.
Also I doubt if any one of the earlier guys claimed for himself the status of the final word. In such a case I would give a benefit of doubt to everybody involved, treating all attempts as ‘valid attempts’ if not ‘valid conclusions’. No finality getting ascribed to any. KLP Dubey ji claiming that everything after the 3 Vedas are distractions is one more matha. Valid attempt indeed. Valid conclusions, well let time prove that. Since it would be prudent to believe in conspiracy theory only after witnessing a reasonably long duration of actions, I personally vote for AV, Brahmanas and Upanishads to be a few more efforts of fit and proper entities, not the isharebazi of some indulgent fools. The fact of life remains that on the whole, things look very amorphous with no clear boundaries. To claim otherwise would be at least superhuman if not supernatural and humans being natural are to work in this very natural restriction, practicing Vedas or otherwise.
I know one thing for sure. Any grammar that does a lesser job of acknowledging the various past will eventually count itself out moving forward in time on account of internal inconsistencies itself. The grammar used will also have to be independent of the sounds/knots/mnemonics/crests and the gaps/aspirations/troughs/WTH. Once this is realized, Vedic practice becomes an important thing (perhaps the most important thing), but not the only important thing.
At this point what baffles me is, why bother with Vedic practice if the practice cannot be extended to its full bloom. What is the point of going on with it if it does not directly or indirectly at least help us in our other pursuits that are also a part of existence as such.
A few things I am gradually becoming very sure of:
1) Even practice of Vedas everyday will not suffice if a person is unwilling to let go. Let go in order to free up the hands for a better grip.
2) PIE is the average of/based on extant sounds, so if the definition of extant changes that would change the average.
3) Vedas are the base/prime sounds tied up through some grammar a phoneme-mala driven into a kind of Shabdmala driven towards perfection. Since it is not an average so the only way it can be challenged is by striking at the Shabd. Nobody in their right mind will attempt to attack the phonemes or the gaps between the Shabds or even the grammar

.
BTW can we say that every composite has a prime divisor that would still return a whole number.
I think I have allowed myself too much of a leeway.
Pranaam.