I tried this tool, it certainly works, but I got a few problems.
First of all...
When trying it to Mega Man Battle Network 6 (U), it works, but the Soundfont just crashes my players, editors, converters...
It has WAY TOO MUCH instruments and I can't even convert it to DLS for other uses.
The only player which actually worked, timidity++, the MIDIs didn't play right.
I tested it on Mother 1+2 (which for some reason... only finds Mother 2 songs, also MIDIs doesn't play right too, the SF2 is fine though) and Mother 3 (no problems with this one, could even make songs: http://www.youtube.com/watch?v=ioW5ecphefA
Other than the notable problems I got, it works just fine. But as a request, I'd like to have separated SF2s for every voicegroups (with the offset to that voicegroup) instead of having all in one. Also maybe folders for each voicegroups with the SF2 and MIDs that uses it.
I think that would be better to have.