i'm looking into getting a digital multitrack at the moment too in the 200 quid range. to be honest, i didn't find anything that is totally ideal.
the boss br600 is definately good (it has a sensible USB implementation), but i think you can get more for you money.
the problem with some of these zoom units is that they just sample at 32khz, although the up to date ones are 44khz, so its worth checking.
i'm also looking at the:
Zoom H4 (it has a builtin 4 track, and works as a USB sound card)
Zoom MRS8SD (make sure its the SD version, the older version takes smart media which aren't as large, both have MIDI)
Tascam DP-01 (massive hard disk, MIDI and SPDIF out, it is big in terms of physical size though)
Fostex MR8 Mk2 (proper XLR connectors, MIDI and SPDIF out, i was reading the manual, and it seems a slight pain to get stuff off it on to PC although it is possible)
I guess we have slightly different priorities. I'd like one with MIDI and SPDIF I/O, I'd even be happy with just a 4 track. I'll probably end up with the Zoom MRS8SD, but its not ideal. I think the MRS8 compresses the audio with some algorithm and you need to use some propritry software, which isn't ideal either.