I went from a 4 shoe in the Losi to a 3 shoe on the Associated and really like it. For me, the 3 shoe "felt" fine but the shoes lasted considerably longer. After the Associated I went to Tekno that basically runs a Losi clutch (4 shoe again). The "feel" is again fine but it seemed to wear more. I'm running the Werks Pro clutch now (4 shoe) and the shoes last considerably longer, feel just fine (again) but the biggest thing is ease of maintenance; it is so easy to work on!
For me, I like the 3 shoes (the AE unit at least) and the Werks 4 shoe the best. I have a 3 shoe LRP in the pit bag that I won at a raffle last month that I might try out.