I've now had a chance to skim the manual and it does look there are some "gotchas" with this design.
For instance, it doesn't look as if you could record on a stereo pair plus one mono track. So you'd need to record on four mono tracks. In that situation, with no monitoring pan controls, it appears that monitoring would therefore be in mono. Or you'd record on two stereo tracks and waste 25% media space. I can see track assign controls between left, right, and both (centre) but I'm not clear whether that would apply to recording (assigning tracks to stereo channels on record) or playback. There is a so-called "mixer" page in the menus but it seems only to relate to playback, not record monitoring. Ideally, that page would provide record monitoring facilities too, together with pan controls per channel. On the face of it, that would seem to be the sort of thing that could be fixed in a firmware update. But as it stands, for the kind of thing I do, the lack of proper monitoring control (unless you take along a monitor mixer too) would be a dealbreaker. That's a pity.
More than 25 secs of pre-record is pretty cool, though.