The SB-246 is cool but I´d go for a RT-223 because it has a broader palette of sounds to play with (including a better selection of bass sounds).

IMHO the SB-246 works better as a stand alone machine (most samples are already processed so it seems a bit pointless to add too much stuff on top of that). The RT-223 seems like a better pair for a sampler, since there´s quite a bit of space to play with FX and stuff.

A working/cheap RT-323 would be even better but would take more time to master.