My buddy had a jomox 999 for years. IMO its a pretty thick and impressive sounding drum box on its own, but it felt like you really needed to dive into it with eq on each sound in order to get it to fit in the mix. The one sound on it that I never really clicked with was the kick. It also had pretty limited sound sculpting from what I remember.
The RYTM is a far superior hybrid drum machine. The analog side is way more flexible in terms of sound design, and I like the sound character better too. It also has sample playback capabilities on each track in ADDITION to the analog engine, and running the samples thru the analog VCA, VCF and overdrive really add life to whatever you put through it.
The RYTM's sequencer is lightyears ahead of the Jomox, has flexible audio routing and individual outputs, and killer built in FX, including a pretty rad analog stereo compressor. Its my favorite all in one box from Elektron. It's fully capable of making complete tracks on its own (the most recent track on my soundcloud is 95% RYTM). I definitely have my gripes with a few design and workflow quirks, but the RYTM gets me where i need to go, and in such style.