That's a very interesting line of sound chips, though for some reason, 4 out of 6 motherboards with a ymf740 are full ATX.
Aside from the MU440EX, this board sounds like it could be nice to have:http://www.motherboard.cz/mb/soyo/SY-6IBM.htm
It's also got on board ATI128 video. ... so, I guess it would be most useful for a win9x box.(though some games back then complained if you were running in too high color mode)
One thing I'd be worried about, it's by Soyo, I heard of reliability problems with that. (but then, this board has a BX chipset, maybe it's exceptional)