I'm a little late to this conversation but I'm going to throw in my 2 cents anyway. I'm 6 ft and about 300 lbs and was never really satisfied with the bikes I got until I got a 94 CBR 1000f, anything smaller than a 750 didn't have enough torque and most of the other bikes seemed to be built for 5 ft 150lb riders. I've ridden almost every type and displacement and style out there from 1800cc cruisers to 500cc full on racers (I was lighter at one time) and I will say it all depends on what YOU are comfortable with. Getting a bigger bike made little difference with me because I was used to bikes with twitchy throttles and slick tires. It may be more than you are used to but so was the F2 when you purchased it. Just be careful all the time on any bike you are on. Learn the limits of the bike and yourself BEFORE you get into a tight situation. ANY bike can get away from you very quickly no matter how long you have been riding if you aren't careful.
Oh I forgot to mention the one downside to the Bike I got...the cost of replacement plastics...remember it's not IF you'll drop it but WHEN.
Either way, good luck with the bike and be careful.