Just had a quick look at Syntrax editor. Good concept and has some good potential, but alas for someone who services multiple clients with music this system is too slow to compose on.
Usually it will take me about 3-6 hours to write 2-3 minute XM track for a game (complex). Due to syntrax being a mouse driven editor it would take too long to get anything decent created to make it worth while. I do like the use of a pattern sequencer per part. This is great OO use in music (some re-usability). I think SID Tracker did something like this on the C64.
I found that when you make timing mistakes in Syntrax you have to basically re-write the pattern from then on everything (including all the FX and volume, Slides). Doesn't help you can't hear the background playing while playing a pattern to hear if your notes are in the correct slots.
Perhaps if there was and editor for Windows which could import midi, or more like a tracker interface instead of the tedious mouse driven editor, it would be more viable option for composing game sound tracks.