I'm gonna have to vote against this also. The only way I can see this being realistic is if it were used like "shouldering" your weapon. Aiming around like that really can't happen while looking down the sights at the same time.
You absolutely have to see it as "shouldered", and not as aiming with a perfect cheek-weld, thats the tradeoff here, it gives you alot of the freedom you have in real life, to see and move and so forth, but you pay for it by not having that perfect cheek-weld profile (but it too is unrealistic if you cannot also do all the other stuff, and we can't, "realism" in games is fickle like that).
Personally, i'd rather have the freedom (but what i'd really love is if we could have both, tap the IS key to bring it up to shouldered with freeaim, hold it down to go for the cheek-weld look! i'd even be willing to have the Freeaim IS more of an "over the sights" view than "perfect aim").
Also, you lads who have only seen this in action in ARMA, that may actually not give you a very good impression, because IMO, ARMA did it wrong, it gives you so much range of movement it's allmost silly! and turning to look at something becomes a chore!
It works sooo much better with only a bit of movement range, like INF had it, thats the way to go.