Going to come back from the dead to ask this question: do all iron sight mods use some form of FOSE?
I seem to be missing out on some nice mods simply because I'm stubborn and want to stick to GFWL (friends and achievements), but have been begging for an iron sight mod from the beginning.
If you're willing to do some legwork, you could probably use http://www.fallout3nexus.com/downloads/file.php?id=6938 mod. According to the mod's description, it does require FOSE, but you can just use the animations and swap the models around yourself in FO3Edit or the GECK. You lose the in-game configuration functionality, the screen blur while aiming, and such, but the iron sights aiming certainly does work. I do use FOSE, but unless FOSE has some modeling- and/or animation-specific features of which I am unaware, this route shouldn't need FOSE.
I use Awrens tweaks+RH_ironsights mod+the sprint mod.
I haven't had any problems. except i've noticed that sometimes when I crouch, the gun won't properly center. I've noticed that this hang up usually happens after I switch from a Melee weapon.
That's a known problem. I get it too, and it's apparently related to opening the PipBoy while sneaking. I just double tap Ctrl (my sneak button) to fix it.