It's a great unit, very versatile. I wouldn't put it 'in line' with my airchain, though. It would be fine if you could sidechain it in, say an aux send/return loop. Perhaps a small mixing console with balanced in/out, inline with your chain (AFTER the processing, and BEFORE the STL) and the effects processor on one of the aux busses. That will keep it clean and give you immaculate control over the amount of reverb you inject into the signal, as well as allowing you to bypass the internal mixing of the MV4. You just run it completely wet and do your injection level on the small console.
It will also allow you to tweak the settings of the reverb program (decay, pre-delay, etc.) OFF the air by monitoring the return channel in your headphones, then when you have it where you want it, you pot up the return fader and presto! your 'verb is on the air. As an added bonus, it would allow you a finer, final level control into your STL, without having to screw around with a bunch of digital menus.
-A