Would you be willing to post a picture of this stock or a picture of you holding this rifle? I can't quite picture this setup and I am very curious what it looks like.
Unfortunately I am on a business trip and cannot take a picture of it. However I think that I can give you a good idea.
Here is an M1a with a standard stock:
Note that the comb doesn't quite get lower than the bottom of the foregrip.
Here is a pistol grip version:
Note how the comb doesn't get much lower than the *top* of the foregrip.
I have a custom pistol grip stock where the comb drops at a steeper angle aft of the gun's receiver. This, combined with some see-through scope mounts that put the scope a little higher, allows me to put my chin on top of the comb and look through the scope with my left eye.
Another option I looked at instead of a custom stock was an Archangel stock.
Imagine removing the cheek riser altogether. Unfortunately, the resulting comb would still be level with the bottom of the foregrip, just like a standard stock.
The stock I have isn't as "tacticool". Just imagine a pistol grip stock with a bit more of an angle than this one:
Or this one with the cheek riser removed and a steeper angle.
You can see how I could put my chin on the top of the stock and see through the scope with my left eye.
Yes, the lower butt increases muzzle rise when firing but this weapon is not designed for full auto (or at least they gave up on it).
The see-through scope is higher and makes for increased parallax, but that can be dealt with by good range finding and/or a double intersection bullet trajectory.
My opinion is that a weapon with good ergonomics is more comfortable to shoot and thus lends itself to better real-world accuracy.