Which do you prefer? Disadvantages/advantages to each? I've got a Mk 3 I love but wanted to pick up a tactical for the threaded option. I don't mind the mark III grip but I like the feel of a 1911 as well. Can't decide between the 22/45 and the mark IV.

Get a 4 22/45 lite for the supressor.
My wife has the III.

I like both and have a few of them. If you're going to buy a suppressor I don't think the III/IV come with threaded barrels but could be wrong. I just bought a 22/45 Tactical that is a bit heavy but shoots really nice if you like the weight and feel of a 1911. The Mark III/IV are both way more accurate than I am. Ignoring the potential for being a suppressor host, I like my Mark IV Hunter best so that's what I voted for. But the 22/45 is nice...

I just bought a 22/45 Tactical as well. I haven't had a chance to shoot mine yet, but I'll be taking it to the range over the next couple of weeks. Glad to hear you like yours.

Owning both, I'm amazed to see the 22/45 ahead in the poll since the MKlll and MKlV are far superior in every way except for acting as a suppressor host.