I am about 270ibs and 55-60 MPH is about maximum on my bike. The rear tire is a fat, heavy ATV tire.
I am about 5'10" or so and I feel a little cramped on the bike.
Having said that I have had many dual sports and the TW200 is the work horse that I will never sell. I enjoy riding it and have made some mods to it that increase the fun factor.
My wife loves this TW.
If you outgrow it, you can always sell it and get much of your $$ back. Or keep it and get a bigger bike. The DR650 is a good alternative to a TW200 (at least for me).
mine on a nearby farm road.