You might check out the Roland DR-880 demos. Pretty good, IMO. Mind you, no bass following, but it's got guitar and bass amp sims in there

Got a pretty decent live feel to it, I thought.

Your options with an arranger module these days are pretty much Ketron and Ketron... Mind you, a nice PSR probably weighs not too much more than the Ketron (7kg to 11kg). I know it's not what you want, but arranger modules are pretty much a thing of the past. If you want modern features at an affordable price point, you may have to go to a keyboard...