Jurgen 475 pounds is not that heavy of a bike and keep in mind that if you drop it you have the leverage of the wheels to pick it up. You really will only be lifting about 100lbs.
I think an older BMW would be a great bike to learn on as they are pretty forgiving. That R90 has plenty of power for you.
I have been in the hunt for a older BMW and am driving up to Wisconsin on Friday to pick this up:
Here it is with the hard bags:
For some reason Missouri has a number of these bikes also so try the St. Louis, Kansas City craigslist ads. But for the mother of BMW ads this is the place:
The IBMWR Marketplace: Home