I used to have one of these ages ago and it was incredibly useful. But sadly I got rid of it. Why? Good question, I’m not even sure now. But I needed a new one even though I had the V4 as well. The big difference with the V3 is that it has its own power from a little PP3 (9v) battery inside. That means that it can power devices that draw vampiric MIDI power, such as the two MIDI vampires I’ve got.
All in all a very useful device indeed.