If you're sliding forward the seat angle is almost guaranteed to be in need of adjustment.
I'm not sure about the 2.1, but my 1.2's saddle isn't that great. being that its all I have and I don't feel like buying another saddle till I'm a bit lighter, its what I use because its not that terrible either once you get the adjustments right. keep that allen wrench with you and TWEAK TWEAK TWEAK. it can't be said enough that adjustments to the saddle are best made on the road (well, the side of the road) where you feel what's wrong and probably immediately feel what changes with the adjustments. Keep the adjustments small.
Sliding forward = seat angle too low.
crushed nuts = seat angle too high.
assymetric sensation = saddle nose not centered on bike
"heat" in perineum or hip socket pain = saddle too high.
knee issues often relate to the forward/backward positioning of the saddle and sometimes to the saddle being too low.
Low saddle also causes a pretty dramatic loss in speed/climbing power.
corrections to the above are welcome, I'm no pro but this is what I can remember/have experienced.