Been trying to do a ISA only ship run, and while I`ve been able to get a good amount of support vessels(i.e carriers, missile boats, etc) that preform well(though the Connecticut is kinda underwhelming in the firepower department), for mainline ships I havent found any that can compare to Sector vessels(atleast in frigates and destroyers, sofar), for ex. testing against a BRDY Scorpion destroyer, I havent been able to defeat it in the sims using a 'line' vessel(despite carrier and missile ships managing it, as well as other Sector vessels), mainly due to the fact ISA ships are made out of paper(i.e California has 100 armor and 1.2k Hull, died to 2 harpoons from full hp), and they have lacking shield arcs(usually 90, which leads, combined with paper thin hulls, to death in under 10 seconds to a single flanking ship). I think you need to buff the resilience of the ISA Ships.(and likely the FTG, XLU, etc, in addition to buffing burn speeds(i.e a XLU crusier shouldn`t go 1 burn slower than an Onslaught)
EDIT: Also, unsure if its a bug or not, but none of the Steelclad ships seem to have preset variants in the refit screen, unlike Sector ships.
EDIT #2: Also, Steelclad may be stopping other mods from displaying missions as no other mod(despite me having multiple mods that add missions such as the Kadur Theocracy and the SCY) displays missions in the mission screen(and Steelclad seems to affect the menu screen alot, with Steelclad music in the background and only Steelclad vessels flying the the background aswell, it might be a holdover from when you ported the mod over to 9.1)