Just realize there is a format called 'Premodern'. I think its better to just focus on either Premodern or Middle school and promote it big to increase the player base and interest. There is no use to have different small formats.
They are very different formats though. I'd never be interested in Premodern with their banlist, for example.
Premodern seems as unexplosive as Modern considering their banlist. Middle School seems different and probably warrants distinction from other formats.