Mornin' Questor: I've handled a couple of longslides, an earlier AMT in 45 and a custom Clarke in 38 Super and I think they are sweet pieces. Very easy on the recoil - the longer slide seems to tame that a bit. If I recall correctly - and that's a stretch - the spring had to be a bit lighter and longer I think, to get everything to function properly.
The longer barrels in those two pistols were very accurate and on occassion I see one of those longslides and drool quite a bit thinking how much fun it would be to shoot one again. As a target piece I found both to be very accurate - the feel a bit different in the hand, a little barrel heavy although the additional amount of weight is only a few ounces, but it sure helps with that second shot.
I think that were I able to obtain one I would like it chambered in one of the 45 acp wildcats - either my own 40 caliber cartridge or the 40 Super, which is close enough to provide me with a good supply of workable brass. The benefit would be the increased velocity and sight radius. Great for silly-wets and medium game. Now, having said all of this, the last one I saw was a custom chrome longslide in 38 Super. Oh Yeah! Mikey.