MIDI is (IIRC) only around 31Kbps serial, so latency shouldn't be a huge issue. Dropped or out-of-order messages on UDP is much more of a concern.
Are you trying to control something on the PC specifically, or just MIDI in general? Just curious as I have a number of ethernet-capable .NET Micro Framework devices sitting around here, and have build MIDI implementations for a few of them.
I haven't done anything with wireless MIDI. Looks interesting.