If you have midi on your Monotribe you will know how much fun it can be, however recently I have discovered that not all Monotribe midi interfaces are created equal.
If you have bought a midi interface for your Monotribe here is what you should expect:
A ground connection on the Midi output - I know of one popular kit that does not have this, why? All midi outputs should be grounded, it is part of the midi spec.
No lag on the midi input - the Monotribe is capable of responding to midi as fast as any output can send it, and you should not get stuck notes either. If you experience this it is possible that an unsuitable opto isolator has been used.
No stuck notes or lag on the midi output, with a properly made interface this should not be happening, and one of the reasons why ground should be present.
All midi interfaces for the Monotribe allow the same functions, this is coded into the Monotribe firmware, so apart from performance issues mentioned above and price they are all the same.
Needless to say, I use a fast suitable opto and midi out is grounded on all my midi kits.