Cannot speak for the midi, but I can't imagine Roland doing it wrong
If I were you, I'd take a peek at the MIDI specs in the user manual online.
Any surprises about implementation should be noted by footnotes or warnings.
No footnotes or warnings to speak of. Short of the standard implementation charts with the X and O indicators, manuals rarely do a good job at telling you what a board
doesn't do (or what it does poorly). While you can pretty safely assume that it does not do anything the manual doesn't tell you it can do, it can take some MIDI knowledge and sometimes "reading between the lines" to figure out where the omissions are.
Some notable MIDI shortcomings in this case are that, while you can store 100 user registrations, you cannot select them via MIDI; and that the nine sliders do not send MIDI CC, but rather only send sysex commands, which complicates its usability as a controller.
But people have different needs. OP says he wants "a good midi controller for a DAW" but that depends on what you need it to do. If you just want to enter notes played on the keyboard (and pitch/modulation lever and foot pedals), that's easy. If you want a bunch of controls that send MIDI CC, it won't give you that. If you want DAW transport controls, it won't give you those either. And if you want keys that will be properly expressive for recording piano, you may prefer a different kind of action. I guess the point is, its suitability as a MIDI controller really depends on what you need it to do. Pretty much any board can be a MIDI controller to one extent or another, but this board is not among those that are specifically designed to have a lot of controller functionality.
I will likely be using a pretty equal mix of piano, EP, organ, and synth sounds.
It's fine for that (assuming, of course, that you like its piano, EP, and organ sounds, and its action). A few other things I think are worth pointing out:
... It's best at playing one sound at a time. If you want to split or layer two sounds (which is its max), there's still only one set of effects, so, depending on exactly what you're doing, either both sounds will share the same effects, or only one of your two sounds will have effects.
... There are only 5 front panel controls for altering a synth sound: attack, decay, release, cutoff, and resonance. For any deeper editing, you need to use their iPad app, or a freeware third party editor available for PC/Mac. (That app, BTW, adds a whole bunch of other useful functionality to the board, including a lot more sounds.)
... For live recall of your up-to-100 saved sounds or sound combinations, there are only 4 hard buttons for single-button patch select. You'll need to scroll to get to additional sounds. (This is also where the aforementioned limitation of not being able to select those sounds over MIDI comes into play.)
For about the same price as the VR-730, you might also want to look at the Fantom-07, which can also cover the piano/EP/organ/synth needs but also has tons of MIDI functionality, more split/layer flexibility, touchscreen patch selection, full on-board sound editing, etc. But the VR-730 still has some advantages, e.g. it has 9 drawbars (the Fantom-0 has 8 sliders, and you have to use the touchscreen to get to the 9th), or you might like its action better, or prefer its simpler front panel operation.
