It's hard to tell if it'll be powerful enough for you. It starts with your expectations, goes on to your physical build and where you ride most of the time.
The Sprint delivers about 120 HP and doesn't weigh a lot more than a Versys (~70 lbs, IIRC). I don't think it'll be stretch to say that it would feel a lot more powerful. If you live/ride in one of those really flat states where it seems motorcycling is limited to testing how fast you accelerate (or how fast you can go before they pull you over and take you away
), that may be an issue. Also, if you are a big guy, there is only so much 65 HP can do, even on a 400 lb. motorcycle.
The Versys has no problem cruising at 80 or even 90 MPH. With the right windscreen for you, it's actually rather comfy at those speeds (so I've been told, I wouldn't ride that fast in the US, of course...). It vibrates. It's different than the vibrations on other twins like the V-Stroms (because it's a parallel twin) and definitely different that the triples and inline 4's. To me, I-4's are the worst, they produce a high frequency vibration that gets really annoying on long rides, but like seats, windscreens, etc., it's a very personal thing. I've read people say the Versys vibrates too much for them to be comfortable (yet they seem to be happy on a Ulysses
), but it doesn't seem to prevent me from doing 500-700 mile days and enjoy it.
If you ride more mountain roads than flat ones, peak HP is meaningless. Torque does make a difference, so on a smaller displacement bike you have to keep the engine spinning in the right range for maximum acceleration. If you are lazy with the gearbox, it just wont accelerate as fast. A Sprint may rip your arms off from 4K on, the Versys will pick up speed at a slower pace from that engine speed. OTOH, if you keep it spinning near peak torque, it'll move along pretty smartly. Enough for me to keep the squids on sportbikes scratching their heads...
If you are set on keeping the HP at around 100, take a look at a V-Strom 1000. It has a very comfortable riding position (it's roomier than the Versys) and the power you seem to be worried about. But it also weighs more and loses some of the sharp handling that comes with smaller, lighter bikes. I still have mine, it is a very good two-up touring bike.
To settle the power question in your mind, think about the times you were at full, wide open, throttle. How many of those times were you in the upper powerband (say above 6K rpm)? How often does that happen? If you do that often, maybe you do need a more powerful bike than what is offered by a 650cc twin...