A friend of mine has one and I think its a great bike. I wouldn't hesitate to ride one across a few states. I've ridden it at 75-80 and it runs along just fine.
I have never ridden the Scrambler myself, however a friend who was visiting from Denmark rented one for the few weeks while he was here. We rode up to Yosemite Ca ( about 300 miles) On the freeways I had to hold the Rocket back at around 50 - 55 mph because he had no windshield and no full face helmet and just couldnt keep up because of the buffeting, Other than that he really enjoyed the Scrambler,
On a side note.... riding around the streets of San Francisco with somebody who doesnt understand our traffic laws can be quite the Harrowing experience!
I own the scrambler's sister bike a Bonneville SE and the engine has no problems at 77-80mph. A little bit of wind protection is a good thing on these bikes.