I'd be happy with just a free-IS movement like in Infiltration.
I would like that too, I really think if the RO devs tried out that system but tweaked and modified it better, I really think it could work well. And if they added in weapon colission when in IS then I think it would be really cool.
(I should make a topic about that whole concept and see what people think.)
But as for how your sight picture looks while moving when in IS, I think it needs to be changed a little. Because even if your rifle WILL make an accurate shot if your sights are aligned properly, the changes that a soldier has the ability to keep his weapon that aligned WHILE moving around in the middle of combat seem far-fetched to me. (Not that its impossible, but in the midddle of combat its probably a rarity.)
What I would like to see in RO is when you move your weapon side to side in IS, your fore and rear sights will un-align besed on the direction you moved your aim and how fast you moved. (Much like how CoD does it.) This un-alignment of the sights would just re-align after you stopped moving, and the speed at whcih they re-align could be based on your weapon (weight, length, etc. . . ) and maybe how much stamina you have. And of course you could still shoot if your rifle was still un-aligned, but you cant expect you hit your target all the time.
I'm also like to see the normal weapon sway when standing still have some more variation between the fore and rear sights instead of being rock-solid aligned while the whole rifle is wobbeling all over the place. I'm sure if you were having trouble holding your rifle still you wouldn't be able to keep them perfectly aligned either.
And that idea could also work with an Infiltration free-aim-IS with no problem.