Have you calculated how much sail area you will lose by going the thinner jib that may give you an indication on performance loss. On the Taipan 5.7's they compensated a bit on the kite boats by having a strut from the bottom of the bridle to the spin pole so the jib could start much lower that added area but still didn't compensate fully. I have a PDF for the Taipans I'll try to upload
sorry can't upload a pdf