One point not made yet is that ABC engines don't tolerate being run rich as the liner must heat up properly to provide the necessary running clearances but engines with bushings kinda like a little richer mix as noted by several comments above. For this reason I'd not choose an ABC motor without bearings.

I agree completely that bushing bearing motors are generally given a bad rap. I've bushing motors like an Enya .29 that is probably older than me and I'm not young (sixties) and it is still going strong and currently flying in a Sig Kadet LT-25 trainer for the grandkids. It starts easy and idles great but admittedly likely has less power than a modern .25 but in those days prior to electric starters, easy starting was a priority. And... regarding air bleed being non desirable, yep... the old Enya had air bleed idle and is one of the most reliable idling engines I've ever seen.

Perhaps my illustration just points out that there are always exceptions... but as someone else pointed out very well, one can't classify them all because of one either.