I'd use a dsPIC30F4011 that has built-in CAN, but the dsPIC30F2020 has a lot more stuff I need- the only thing it is missing is CAN (it has current limiting, built-in comparators, lots of fault lines, fastesr ADC, internal clock dithering, and a ton of different PWM schemes), all of which I need more than CAN. I'm just trying to find a way to get everything with as little effort as possible.
THe only two serial communications pins I have available are the UART lines, and it'd be nice if I could get some multi-master, differential, error-checking type protocal in without having to do it in software since the uC will be doing some time sensitive things (and I might exceed program memory if I try that in software...or I'm just lazy.).