Mr. Clark:
I have the HT M40A1 w/Bipod and An/PVS-10 Scope, M40A1 w/TASCO Scope (SEAL Mtn Sniper), and the M40A1 w/TASCO Scope & Silencer and they seem to work well with ACE, BBi, DML, and of course HT bodies. They seem a fraction larger but it works. I also have the HT M14 SOCOM II; M14 SOCOM A1 w/HOLO scope, Surefire M900 Millennium Grip, and silencer (CIA COI), the SAGE MK14 MOD 0 (ERB), and M4 SOPMOD w/Duostock. These weapon seem right on the money.
As far as the M40A1 vs the M14 SOCOM A1 w/Silencer, I will go with the A1. But that is me not wanting to carry two different weapons that can do the same job. They both can fire the same round (NATO 7.62 X 51) but I can get some dual purpose use out of the A1. I would say work on the concept of your figure first then choose the rifle. You are going to have some real hard choices when the HT series 4 comes out. There are just some sweet weapons in that group and the M17 LB w/Silencer is not making it easy to choose a sniper rifle.