Wow, this thread is still alive. LOL.

I've had my S40 on the highway a couple of times, and yeah it's not that comfortable at 65-70 mph. My came with a windshield that I took off...now that's it's chilly, I will prob put it back on to deflect some wind.
OK, thanks for all the thoughts on the S50 and similar models. I saw the Kawasaki Vulcan 900 mentioned...I've seen all kinds of good reviews on the Vulcan 750, 800, 900, etc., so I may give one of the Vulcan's a look at some point. One thing that strikes me though is that most of the other bikes with displacement simlar to the S50 are quite a bit heavier...the S50 is by far the lightest at about 440 lbs wet. I kinda feel like the S40 is just a tad too small (legs wise)...thus my thinking that maybe an S50 would be the perfect fit. But hey, everyone has different likes and dislikes, and you really don't know until you ride it.
I'm in no hurry to trade up, btw...I definitely love the S40, and would highly HIGHLY recommend it to any beginning (or re-beginning) riders, or someone with a 250 who wants to move up. That said, I still need to look at raising the seat a little...that may drastically improve the comfort level.
Cheers!
Dave