Andrew I am 102kg and looking for a one up boat and have found no problem getting offers to ride one and I would say go for it. Last Saturday I was leant an older A for a 17km regatta on a day that went from laying under the mast and bagging up to on the wire and tight as with wind shifts. They are a really satisfying boat if you like instant response to any alteration. The other thing I find attractive about the light boats is I can tie it high in the shed above the Stingray and only use up one boat space in the shed. Im no expert but from what I've read heavier guys like us get sails cut fuller to power up and seem to lower the diamond spreader tension if they need to flatten the sail a bit.
regards