Incra TS systems

I'd be interested in hearing some of the pro's and con's regarding the Incra Tablesaw systems.
I've no doubts about the accuracy of the units...but..
how about ease of use...
how much extra room on the positioner side is necessary...
does the positioner get accidently bumped around a good bit?
if so, does it stay put..
How functional is the fence?
Is the fence easily adapted for specific jigs etc...
Durability?...

thanks in advance
bill