I'm 6'3" 230lbs so I understand your concerns about engine size on the bike. I've had 250 cc dual sports, 600 cc sport bikes, and a 750 cc cruiser. And everyone of them was fine for pulling my big ass around. I've ridden some friends zx10's and R1's and they're amazing, but nobody "needs" one. I'm not calling anyone stupid for owning one, but unless you do track days and can ride balls out you'll never use a 600 to its full potential. I'd say go with something like a used CBR600 F4i. That was my favorite bike out of everything I've owned. It was big enough body wise that I didn't make it look tiny. And the 600 was more than enough motor. And if it ever get to a point you don't think it is add a smaller sprocket in the front or a bigger in the rear and it becomes a completely different bike. It's well balanced and easy to ride. R6's are awesome bikes but are definitely a sharper tuned bike, so they're not as forgiving for beginners. You could get a 250, and they're a great option for commuting, but understand that's what it'll always be. You can ride a 600 like a 250, but you can ride a 250 like a 600. My point being if you're responsible, sensible, and don't ride like a d-bag you'll be fine. And for a guy your size I think you'd want to upgrade pretty soon. Pay attention to everyone else, buy good gear, AND WEAR IT. All the gear, all the time. But whatever you decide to do keep in mind this won't be the last bike you ever buy. So even if you start with a 250, as long as you take care of it you can get your money back out of it. There's always someone looking for a beginner bike. Just take it slow, be aware, and never ride above your skill level. You've taken the class so I'm sure you probably have a fairly solid knowledge base to start with. You'll be alright. One of the best things you could do is hang around a local bike shop and find an older guy who still rides sportbikes. They'll teach you more than you could ever imagine. Let me know if you've got any questions and I'll help you out as best I can.
