I'd say limiting cav should be the last option we take.
as aedor said, with the new rule 1k gold and reducing combat and round bonus have big possibilities to change strength of the cav. we might better to see gold would solve cav problem or not first. if cav spam would easily be defeat, there is no point limiting and i think we better to remain cav spam as one of the tactic.
can't organizer try to set trial tourney (all matches are training match) and report to organizer what involved clans though with new rules. maybe try without cav limit and even if clans found cav spam is too op or boring, organizer can add limit in the real tourney. opening without proper test would occur some problems in the middle of tourney and might mess everything up. it doesnt need to a tourney but something you can simulate the new rules.