Got the HXS (main board) and SLO (small board). Needless to say, HXS is wayyy more versatile. Some great tones to be had, with amp/cab sims, comps, drives, effects, eq/hpf/lpf, the works (and some work better than others). You can have fun getting lost in all the options (and TB threads). But what's fun at home is less fun adjusting live. Learning curve isn't terrible, but not a 10-minute thing either. If you can get used to switching between presets or snapshots, and confident you have "your tones" set, you're golden. But if you need to make frequent minor adjustments live, you might feel flustered (finding options, changing wrong things, forgetting to save, etc).
SLO is almost the opposite – somewhat a one-trick pony, but a great trick. Does a nice grind, a little too much too soon perhaps but the 12AX7 can be switched for an AT or AU with more clean range if preferred. Also hit-or-miss with the simple tonestack eq - you might love the tone most of the time, but other times struggle with lack of mid control. Does have a nice bright switch if you need to cut through quickly, and cab sims are a bonus. Also it's a better DI with XLR out, lacking on the HXS.
TL/DR: HXS way more adjustable, much harder to adjust quickly. SLO far easier to adjust, but not much there besides a good warm tone. If I had to pick only one, the HXS hands down, but I don't need to change much on-the-fly. If you can, try both – either are an easy/fast sell (in US at least).
