Care to write down those calculations?
If it were me, I'd go for the Profile, yes it's costing you £40 more, which is alot of money for something which engages less, but you won't notice the difference, going from my bike to a Zoo Python with a Profile, it seemed fine, ok, there was a tiny difference, but it's completely solid, and will not let you down.
Weight wise, I don't think you'd notice it so much when actually riding :)