How about dropping your seat height. I just went from a 80mm thomson to a 100mm stem on my SL and I think it has made the handling much better. They are the same angle.
I messed around with it and figured that I also needed to drop my seat to balance the longer stem. With a shorted stem, you may fell crunched up in the cockpit, this is why I went to the longer one.
At the end of the day, the longer stem feels more stable on the descents! Can you add more spacers below the stem or try a steeper anlge?
I guess I had the opposite experience of jeffus with this, but like I said the drop in saddle height was key! I think it's pretty common for poeple, especially from an XC background, to ride with a saddle set to high.