Yes, the EBR is heavier than the stock chassis. However, my Troy Industries stock is the heaviest one I have on an M1A. It makes the EBR feel light! IMO (and observation from use), the EBR chassis does have a few demerits:
- With the collapsible stock (dual rod) extended 3/4 - all the way out, there is a wobble in the stock. As someone who has used one for it's "intended purpose", I will say that I have not witnessed any loss of accuracy. It just feels a little unstable.
- The EBR chassis prevents a tool-less "breakdown" of the rifle for cleaning (not a good thing, when you're in the SUCK). Honestly, this chassis makes the M1A a PITA to clean!
- Being that the chassis is metal, it is prone to becoming hot in the heat/summer and cold in the cold/winter. Nothing gloves or a little "user-end modification" can't fix though.
Hope that helps.