It`s a lot "geekish", but if you patiently dive into the settings, you can really personalize the way how it should work. I recommend to carefully browse the manual before buy. For pure musicians not fixed to certain tempo it`s a dream machine.
However, for MIDI/synth setups it`s disaster:
1. No MIDI slave possibility
2. Tap tempo is engaged, when you press "STOP" button 3 times, no possibility to turn this off. I thought I throw it out of window during playing sets at home, because I was constatly changing tempo in the middle of the set.
3. If you send MIDI messages, but currently want to stop RC300 from playing, you have to keep one blank track on. Otherwise you`ll stop whole set.
4. No further development, no direct contact on tech support. The firmware you buy with new machine is v1.10, last official release is v1.05, weird... After some time it started crashing with some message (don`t remember which) and I had to reinstall. Luckily it works OK since then.
If you still want to use it in synth setup, please unplug the midi cables and just set tempo manually...