I keep telling myself one of the reasons I got it on PC rather than XBox was in the hopes a free aim mode would be patched or modded in - and then I'd be able to put my mouse to full effect... But I reckon a controller is probably the way to go, at least for now. More than once I've lobbed a grenade in the wrong spot because of all that jumpiness. Best case, they go slightly askew and do less damage; worst, they fall at my soldier's feet and blow him sky high!
Also, I clearly bought the PC version for the anti-cheating mod.