I don't personally own one, but I've heard some good reports on the Tasco World Class and Target/Varmint scopes (Natchez currently has them on sale). Varmint Al (http://www.varmintal.com/ashot.htm
) has some good things to say about them, and if you look at the buyer comments on the Midway website, most are very positive.
For $90 to $120, I'm thinking about giving them a try on my long-range squirrel sniper 10/22.
I am very intrigued by the one-really-nice-scope-for-several-rifles concept. You can only shoot one at a time, so if the switch is quick and easy, it seems like this would have some merit.