Re: in mast furling issues?
I've had three boats with in-mast furling since 2001. Vertical battens in this one.
Obviously I'm a fan.
Keep the sail taut, and don't let it flap wildly when furling.
With the big genoa's most new boats have these days, I really don't think there is much of a performance penalty. Trim the sails and keep the bottom clean and you'll be fine.