"12-14’ so good sized ones. Probably 40hp to 50hp outboard.
Stability, performance, towing attributes?"
Stabilty - always relative but even at 12.5' they are pretty stable, the stability rises quickly with each added foot.
Performance - you can usually get on plane with up to 4 smaller sized adults, travel at 20+ mph easily, and top out at or slightly above 30 mph. Can tow a 'good' skiier if desired with one on board (not allowed in some states).
Towing attributes - at hull speed they are OK. At higher speeds and in weather even the 14' ones often do not have some of the items which mke towing easier such as - self bailing cockpits, longer and deeper beam to resist 'wagging' of the tow, large and robust tow attaching points, low enough tow attaching points. Any of these could be modified as well on existing RIBS.
Dependent upon make/model selected YMMV.