I have a Midiman USB 2x2 and it work perfectly, but as my gear collection has grown, so have my MIDI needs.
Devices I use that I use MIDI with:
Computer
Tascam DM-24
Alesis HD-24
Lexicon MPX1
Alesis Quadraverb
Line6 POD
Alesis QS 8.1
I am thinking an 8x8 is the way to go here, as I should...