Anyone shot one of these or seen knowledgeable review(s). The Air Arms rifle has turned out to be excellent at varmint control around the place, so I want to add a pistol. Anything else out there I should look at, I don't need a one holer just MOR (moment of rat)?

It's like an old BSA Scorpion but not as good.
I'd try to find a used BSA in good condition.

Or just get an HW 45 it is sold as a Beeman P1 in the US.
Buy some nice grips for it and add a little weight in the space in the frame under the grips for better balance.

http://www.beeman.com/p1.htm

Diana 5's are strong for spring pistol but a bit hard to shoot accurate as any strong springer is. Why not try a Crosman 2240? Lots of fun and easy to customize.

There's nothing like a good spring powered air pistol for just great fun out plinking or pest hunting (we'd never do that over here of course as there is a ban on hunting with an air pistol)

The single stroke pneumatics are seriously accurate as are precharged pistols, but they just don't have the magic and the nostalgia of a nice springer.