Topic: Boom length

My Contessa has a roller boom that's 3.45 meters long (11 feet, 5 inches). That's nearly a half-meter longer than the standard boom length listed for the Taylor-built Contessa on and I've never used the roller-feature -- slab-reefing works best for me. I'm considering getting a new mainsail with a foot running the full length of the boom, but I'm worried a sail that large would result in weather helm problems. Anybody else have a boom this long? What size mainsail works best with long booms? I appreciate any advice. Thanks. (I've also posted this question on the Sailing & Rigging forum.)