Matt -
Like you, I mixed on an LS9-32 with splits for foldback. I went to the iLive systems (T112/idr48 and an R72/idr32), which was a step up in about every detail. As I have slowly been backing out of the live sound arena, I sold the T112 as the R72 system took care of everything I was doing. I used a 24/24 split for 90% of my jobs, and had a scene with 32 inputs for the scarce jobs that needed more than 24. (system is for sale, by the way)
You need to consider the FADER COUNT as well as CHANNEL count on any surface that can provide your requirements... You'll need 64 faders for foh+monitors, say 8 dcas, 16 mixbus outs, and if you are including LR in the 16 output, you're going to need a surface with 88 available faders. Add 8 matrix, you're at 96... How about some FX? You could be looking at 100 or more faders needed. In my situation with the R72 (which provides 72 fader positions, 6 layers of 12 faders), I programmed my basic 24/24 scene with 48 channels on the left bank, (8 ch x 6 layers) - except monitor channels 23 & 24 were used for matrix sends, and the right 4 x 6 bank was 4 x dca, 4 x FX sends, 4 x FX returns, 8 x auxes (2 layers) for foldback and a layer with L-R-SUB-Playback (playback in stereo on 1 fader). That worked for me using all 72 faders, but you'll need something with considerably more faders for your plan. Maybe Digico has something? The Allen & Heath boards allow the "hiding" of faders, so for instance, if you had a number of stereo input or output channels, they can be operated with 1 fader per stereo pair. You can "gang" up to 8 channels in 8 gangs, which could save faders...
I think deciding if rackmount is more important than channel count - or vice versa - will help you make your plans. As it is, you need a 64 channel mixer and a surface with whatever you decide your fader count must be... hopefully rackmountable...
Cheers,
-Tim T
