If you can't tell a difference in rpm's between D1 and D2 when you are riding your D1 and D2 switch must not be working because it is not a little difference it is alot of difference. Its like the difference of a different gear selection, like the difference between being in 1st(D1)or 2nd(D2)when doing like 8 or 9 mph. I would say if you can't tell a difference it can't be working properly.
Steve

 

The difference is indeed huge, cruseing a flat trail at 20MPH in D1 would be like 3rd on a 450S, in D2 Its like being in 5th as the engine is just barly above idle and so quiet i often spook deer right out of there bed!

 

There is a huge difference in mine too. I use the D2 for flat trail/economy riding because it keeps the RPM's (at the same road speed) so low compared to D1. D2 sucks for hills, mud or anything else that requires a hard pull...I don't know where the D2=torque comes from, if I'm going to pull anything I'll keep it in D1, D2 won't do the job because it keeps the engine speed too low and seems to be working the transmission too hard.