I use 90 fov also.. (always have done).
my sensitivity is pretty low..most people who used my .cfg are like..wtf how do you play with that!
I also use L for my nexgun..which some will find strange since it is the other side of the keyboard compared to my other weapons, i just stretch my thumb to hit it since i got quite big hands..works for me.
Low sensitivty normally produces much better aiming results in general..so thats the way to go..but you should be able to move relatively comfortably when have it (as in you should be able to move the mouse nicely aiming also..not ultra mega-slow that its impossible then to aim!)
Play with whatever makes you feel comfortable, but a lower-level sensitivty produces better results (for hitscan weapons) like the nexgun, whilst high-sensitivity is better for splash weapons like RL and mortar (why bundy makes much air mortar imo).