Well, it's almost a year later and some of them have held up beautifully... there are no scratches in the paint and look like they were painted yesterday.
Some of them didn't hold up well at all though... they ended up badly scratched. The kid's door knobs were the worst... they were a mess of scratches and looked terrible.
This was the worst one.... what a mess!!
I still loved the look of the ORB, but didn't have the heart to sand, prime and spray them again, so...
... I took the easy way out.
I went to Home Depot and bought a few new knobs to replace the scratched ones. I chose the Kwikset Cove Venetian Bronze knobs because of both looks and the very reasonable price.
So now the kid's rooms and their bathroom have the "store bought" ORB knobs and all the other doors in the house have my "home made" ones.
I also replaced the exterior knobs with the same style exterior knob. When we bought the house there were several different styles of knobs on the exterior doors, most of them at least 25 years old (old enough to be worn out and beat up, but not old enough to be antique!), but now they are all updated, and match, and have keys! (Yes, we'd never had keys for some of our exterior doors... it was kind of a problem!)
So... the ORBed door knob experiment wasn't as successful as I would had hoped... I'm disappointed that the ORBed knobs didn't hold up better, but considering I painted 10 door knobs last year and only had to replace 3, I guess the experiment was still somewhat successful...
I'm working on a new paint project now... sprucing up the main bathroom... but that post will have to wait for another day. :)