Being able to pass audio digitally between Factors would be a welcome addition. I agree, too, that my dog probably couldn't hear the difference (he's likely got hearing damage already, though). To me, this would be more of a concern in recording usage, but not so much in an amp loop (or in front). Still, I'd prefer to keep A/D/A conversions to a minimum.
Some people seem to be averse to running multiple factor for this reason, although in practice I have not seen any issues personally. the AD converters in the factors are very good at what they do IMHO