I have yet to find a sampler that can take several samples into the same key AND play them randomly. Shortcircuit can take several samples but it can only have 1 sample at any given velocity level, it can't have several on the same velocity and randomly play between them. The reason I want this is for programming drums but then again... it's probably worth it getting something like Battery if I'm gonna start programming drums so, it's not really a big deal. It's just cool when freeware stuff can do the same job as commercial stuff, so I'm more inclined at having a freeware oriented workstation.
Anyway, then there is the free version of Kontakt which you can load samples into (not sure if there's a limit to the amount of samples you can bring in though) but Kontakt has a set of very advanced tools to get the samples working the way you want. Lot of options and stuff... but once again, I haven't seen the multi-samples per velocity with random playing as I mentioned