It is very nice to have a bigger bike if you are going to travel any amount of distance. 60-65 just doesn't cut it in a lot of places. 700 miles is nothing in the grand scheme of things, but if you are smart about it, you could learn a lot skill by moving up in size a bit. These mini-bikes are ridiculously easy to control at low speeds, something bigger bikes are not.
I know a lot of very experienced riders on these minibikes because they are so much fun. You don't really outgrow it.
If you are going to get something bigger to go with it or as a replacement, I recommend not going to a 600cc sport bike like so many do. I'm sure you could handle it, but I think moving up progressively in power really teaches you how to make the most of the power and handling you have got. The 300s and 650s are great bikes to learn on and not as uncomfortable as the super sports. I've never owned one, but if I was in your shoes again I think I would get Versys. Those look like awesome all around bikes. Dirt roads, track, touring, 2-up with the wife... ;-)