Protomech, all IC motors will always make more power and torque as the revs rise (as you know) up to a certain point, where the mechanical efficiency drops. The GS500E has always had a lean fueling condition around 4000-6000 rpm since the day it was introduced. Fattening up the fuel mixture by raising the jet needle will make a noticeable improvement in power within this range and I highly recommend this slight modification. It is easy to do and I think you will like the results.
Here is another tip. Around 45K miles my daughter's GS500E started leaking oil past the ignition (right) side oil seal, located on the crankshaft, behind the ignition pick-up. I took things apart and discovered that the original oil seal had worn a groove into the end of the crankshaft and the oil in the crankcase was finding its way between this groove and the seal. I went to my local Honda dealer looking for a cheaper oil seal and they found one of the right size made for a Honda model (I can't recall which one, it was years ago), that was a double seal that would rub to either side of the worn groove in the crankshaft end.
That solved her oil leak problem - at least until her husband borrowed the bike and went on a thousand-mile trip without checking the oil level. Knock, knock, who's there? Not oil, apparently. Even with bad motor bearings, the bike ran another 6000 miles, until it was sold (at 85K miles) to a Mexican fellow who planned to ride it from Seattle to Mexico City. The knocking didn't seem to bother him too much. I guess he figured "they all do that". I hope he made it.