I have the 10v, SL, 2gb RAM. I use Adobe Audition 3 mostly to cut, crop, splice, and pre-mix MP3s - works fine for me, good granular control of my cuespots, etc. I use Soundbooth CS4 too, since I have that on my Windows pc, but Audition is a better editor by far.
I remix using Reason and push out to record - again, no problems.
Live, I play mainly latin gigs, and the salsa dancers really don't value their songs mixed into each other (spoils the grand finale big dip!) so it's pretty much load/play/cue/load/play.... I use a Vestax VCM-100 and its USB ASIO soundcard (although I run it on an external AC adapter to save USB power) which is in front of Traktor Pro 4 decks - 1 for mic, MP3s off the HDD library, an additional USB-powered SATA drive, a USB Korg Nanopad - and I never have any hiccups on my sets. Playback is smooth, no stuttering, and simple loops cue and playback well.
All in all, works for me no problems for up to a 6 hour gig! After that, the problems are usually this end of the keyboard....
DJ Kreol, Calgary, AB