After wrestling with Giga Teleport for several days, and never succeeding in fixing the problem in changing instruments, I went looking for alternatives to achieve midi transport over ethernet (don't need the audio return, which giga teleport offers). One choice is called 'Midi over lan' but the creators have gotten pretty capitalistic since introducing it, and have raised prices very substantially. So ...
Something called Div's MIDI Utilities for Windows offers several really good little programs including midi monitor to see all midi data on a given port and a midi-over-ethernet client and server program that work!
To use the ethernet stuff you also need something like MidiYoke, which sends midi input to midi output. THAT was supposed to have a problem working with Gigastudio, but there is a simple registry change which cures the problem (information at http://www.midiox.com/ about midi yoke and the gigastudio problem/cure).
Resident, yes the audio quality seemed ok on my gigabit ethernet. I didn't challenge it very much, but the sounds came through fine. Don't remember what buffer sizes I used, but tried several variants successfully; there was a pointer somewhere to set the giga teleport buffer to the same size as the host buffer, to avoid apparent cpu over-utilization on the gigastudio computer.