content: Not a problem at all. You'd just be dealing with bits in groups, e.g. two bits per unit. Copying bits? No difference. Adding? Well, your adder takes lots of bits in and outputs lots of bits, so again, no problem. Etc. At the edges of this multi-value logic system you'd just have encoders and decoders, which are pretty trivial, given that you already have buffers and latches.