a stabilizing sail is not a gimmick.
i have one on my 45' steel trawler
. i always set the sail. of course if you are powering head
on into seas then it is unlikely to be working because you'll likely be straight into the wind too, but you shouldn't roll a lot in those conditions either.
as long as you are on anything approaching a beam reach then you'll heel a little and the rolling will be lessened or even stop altogether if the wind is strong enough. then you just have to get used to going along heeled over like a sailboat.
probably a good idea to check the underwater profile of your hull
. if it is a full displacement hull
(rounded at the back like an old sailboat) and it rolls in a beam sea then the sail will help. if the hull is more semi-displacement (flat at the back), then chances are that the sail won't really do much, but then it won't roll as much as much as a full displacement