Its just a matter of getting used to it, i've been playing on high sensitivity in games a while now (i like the ability to make snap movements if i see something out of the corner of my eye or if someone shoots me from behind) so im well accustomed to it. If you are used to 20 dont try going stright to 100 go to 30-35 and then once you are happy with that go to 40-50 unitl you slowly build up to 100.
I've got to admit that with assault rifles 100 is maybe a touch too high for me (80-90 would probs do) but with the DSG-1 which I use the most it is perfect so i just leave it at 100 and accept im losing a bit when I use the SCARAB.
Good Luck.
Edit: Well you are correct in that high sensitivity is faster and minor adjustments
can be harder than lower sensitivity
if you are not used to moving your mouse the smaller distances needed with the higher sensitivity. Like i said its all just a matter of getting used to it.
