Before using your genoa in high winds like 40-50 knots, check the windspeed it was designed for. Most of them are for 25 knots... apparent wind!!
The reason for not using foam is mildew and deteriation. Best thing to do in high winds is furl it completely and set a staysail or smaller jib
When we ordered new sails
we decided to do without the foam (our old jib
did have it) but we reduced the size from 100% to 95%. We also used hydranet material instead of dacron and tri-radial cut instead of cross-cut. The result is a much faster sail with less surface area. It still works okay for furling
it a bit but we almost never need that because the new material and cut (and 5% less surface) let it keep it's shape so much better (can be pulled flat as a blade) in high winds that furling
isn't needed up to 25 knots.
I think too many cruisers concentrate on big size (wow! 140%) genoa's but forget that for anything other than downwind sailing, the shape is more important (and there's better sails
for downwind anyway). Combined with the trend for changing to in-mast furling it is something I have a hard time understanding. The main looses so much surface and the resulting shape looses so much efficiency, it's almost like one tries to make up for that with a bigger genoa. But that results in a unbalanced sailplan, way too much heeling and so much less performance that it's no wonder many choose to use the engine
instead... hmpff, got that off my chest ;-)
Catamarans do better; they tend to go more and more to high efficiency, full battened, big roach bat-wing-shaped mainsails so that today almost all of them have that. Shame they put that rig on two hulls with some sticks in between ;-)