I don't think epic or marathon speed are a good idea for a pitboss game.
Assuming we do 10 turns a week, it will take 2-3 weeks to build the first worker!
Also these speeds favor early warfare, so in a map with close starts (7 or more opponents on normal size), people would be forced to build at least 2-3 warriors and then archers before worker as otherwise they would risk elimination.
So we are talking very slow growth rate but possible early eliminations.
And if random events are again on... then extra eliminations from the barb archers event are again possible (like mine in FCCP).