X tech is rare till after line ships started getting power refits. Fleets never comprised more than 1 X at a time till later years when they began replacing older line ships. Balance issues are upset when fleeting two xships. I'll let you figure that out yourself. You're a smart guy.
Allowing an ICLX to fleet with a capitol ship is probably a mistake. But the others are at least as good as a heavy command cruiser or heavy fast cruiser, mb a little better. But not uber.
What do you think these seemingly arbitray fleeting rules are for, hexx?