Doesn't seem to be able to watch another channel while recording 2 (Not even from one of the muxes being recorded)

Is that right? And if so why - the 9200 could do this 5 years ago.

No definitely not; the watch and record functionality should be the same as the 9200. First thing to do is put the box into standby (with no recording taking place) and then turn off the mains power. Then switch back on and see if things have improved.