your definately going to sacrifice some pinpoint accuracy for quick target accusition but once you learn where the bullet hits within your MOA dot you can get pretty good grouping within the dot.
It's a problem when you plan on shooting passed 200yds. 300yds takes practice and with enough practice you can go out 500yds+
I recomend going with a zoom scope and mounting a mini RDS to the side of it.
this little mount here works great if you don't have a picany railed AR15, it is a scope ring replacement...
it is made to replace one side of your scope ring to allow for a picany rail up top. Then you run a lil guy like this Trijicon Dr.Optic or Pride Fowler.
And this company at the link below makes mini mounts to attach to any sized scope tube so you can run these on virtually every gun you have and you would once you tried it...
http://www.tacticalnightvision.com/mounts_and_rings.htm