The Slayer is a killer Fromme bike. The 2011 has a slightly steeper seat angle so I'm not sure how this will affect downhilling. 2010 and older are basically downhill-AM hybrids, so they are decent, though not overwhelmingly great, climbers. Build quality is great, and hey, you will be buying local.
No, I don't work for RM.
I do work for RM, so I'm obviously biased. I can however shed some light on the advantages of the steeper seat tube. It gives a more efficient seat tube angle while the shock is compressed under the rider's weight, thus putting you in a better pedaling position over the bb. It also keeps the seat a little bit more forward when slammed, so that it's not it the way while rolling down steeper terrain. lastly, the effective top tube length isn't as drastically changed when raising or lowering the seat. I haven't ridden the new Slayer yet, but the Altitude has this feature and I found it made huge difference in all types of terrain.