Where would someone have to go, to be able to look through both side by side and compare? Does such a place exist, anywhere?
TSE has a few Scepters and I think a few ACOGs in stock. They also have a blue, dummy M4 to mount them on so you can try them out. I'd recommend adopting different shooting positions with it to try it on for size.
Honestly, the quality of glass between the ACOG and Elcans are very similar if not the same. I own both and my eyes are still in perfect shape (knocks on wood).
The Elcans have better (read farther) eye relief than the popular ACOGs (TA 01s and 31s), but are comperable to the TA-11s with 2.5".
I only find the shorter eye relief an issue when I'm wearing certain shooting glasses that stick out enough for the recoil to nudge them back into my face - I simply don't wear those when I shoot with my NSN or TA31.
Unless you are getting a smokin' deal direct from A.T., the DRs are overpriced for what you get (imho).
The ACOG along with the Elcans are obviously geared for military use, so keep that in mind - you may find a civilian target scope to be a more suitable optic for range use (wider selection as well).
There isn't a current military use optic that I know of that is in wider use than the ACOGs - they have a proven track record.