@surfreak @mdubya -- It's interesting, I haven't encountered that much of a problem with feedback. Granted, I'm not cranking the bejesus out of my vintage DeArmond and going crazy loud with it, but I do use a vintage TS-808 for sick overdriven tones in the neck position and haven't had any real issues (as long as I avoid standing in front of the amp
In regards to "hum", well, all great sounding vintage P90's are gonna have it -- that's the tradeoff for the blistering punch of these animals when dialed up... and that's a deal with the devil I'm more than happy to make.
As you well know, you only really notice hum when you're on idle, not playing, etc. so I suppose the secret is just to keep jammin'?