no it doesnt matter where its positioned at all its all preference of the shooter
[quote author=bigdog2003_99 link=topic=219.msg1254#msg1254 date=1288061863]
i mount mine forward for faster sight acquisition, my rifle doesnt need to be 100% on target before i can get a sight picture, again its personal preference though, my eotech is as far forward without the charging handle interfering-until my t-1 arrives
[/quote]
i agree with BigDog 110% tactical stand point its faster sight acquisition and also get to utilize back up iron sights
on a bench shooting perspective yeh i could see closer to your face is more accurate but i speak for myself when i say i do A LOT of Tactical training