2x core + 2x midi to usb pcb

[ultra]

here we go again with another pcb design.  this one is a bit more specialized so i'm not sure i'll find others interested, but i'm throwing it out there anyway.

while making the core/bankstick/iic board, i received a lot of good feedback from others about how to design it, and any help on this one would be good for me as well.

i've been working on a control surface for ableton live.  the basic design is inspired by the one sasha is making (nice work btw) but there are major differences.

my main control area for the 8 tracks has 56 encoders and 64 buttons (switch matrix).  that pcb is all laid out and ready to go.  since i've filled a core, i want a two-core design that can talk via the CAN interface so one core can tell the other which layer it's on so the encoders/buttons can change functions accordingly.

also, the two core design allows me to have separate midi interfaces to the computer.  one is general midi cc's and the other is the mackie protocol to control some of live's functions.  the way i want to use this box (all 16 midi channels available for cc's and notes), i can't simply merge midi.  the downside is using up two midi connections to the pc.  my solution is to integrate two midi to usb connections right on the core, and hopefully add headers that can connect to additonal usb devices.  i want an integrated touchpad mouse on the box, so that would be one.  also, an extra usb connection on the back of the box would be great since i can plug in whatever midi controller (trigger finger, axiom, xboard, etc) i'm using at the time.  thanks to sinesurfer's suggestion, i'm going to try basing the midi/usb stuff on "midinator".

has anybody here made their own usb hub?  i realize it's much easier to rip open an existing one, but i'd like it to be integrated into my pcb.  if i have to use smd components for that part, so be it.

also, is anybody by chance interested in a similar pcb design?