Is there a noticeable difference between the two? I realize the SC-10III has 3" more travel.

Yes. I had a 2000 mxz 700 sport with the sc10 II. I traded it in for a 2002 mxz 700 sport with the sc10III.The sc10 II is a big improvement over the sc10....but I think the sc10 III is even better.It handles the big bumps and the stutter bumps great.I made the mistake of rideing a rev and fell in love.I wish they made a 700 rev.I swear by that motor. :D You can't go wrong with either skid.

Yeah, I put a III in mine, and its a fair bit better, even reusing the same shocks.

What are the travel numbers for the SC-10, the SC-10III and the SC-10III in the REV??

While the ride is better, the most noticeable thing is the amount of transfer. There is definately more transfer in the III. Also, the III bottoms less harshly, and that extra 3" is noticeable. But transfer is the biggest improvement IMO

SC-10 > 10"
SC-10 II > 10"
SC-10 III > 13"