Finally got some loads wired up and had my college age son write some code - so here's 1/ 4 of the board doing its thing!
Four 74HC595's daisy chained to drive 32 AOI518, very low Rds, logic level N-channel MOSFETs. Parts selected & power traces designed for an amp per channel.http://www.crossroadsfencing.com/BobuinoRev17/
Short clip of it working with OE set to 1/255: http://www.crossroadsfencing.com/BobuinoRev17/MVI_2864.AVI
And my son's fade up & down code while moving around the channelshttp://youtu.be/hAVf1D1L-7c
Kits available for $38, plus shipping (US: $5.35) and 4% paypal fee.