I have heard nothing but good things about them and all the comments I have seen range from excellent to awesome. A bit on the pricey side IMO. Advantage Arms is making a 1911 conversion now. You may look at those as well.
I bought the Marvel Unit 1 - after trying it on a Kimber frame I built up a Caspian frame for it.
I put a Ultradot sight on it.
I've tried several brands of target ammo and have settled on CCI standard velocity. A couple types of Eley might shoot a bit tighter but the CCI is cleaner and the accuracy is outstanding.
I did have to locktite the sight mount and the scope rings. The recoil spring rod is what keeps the unit locked to the frame and that has to be locktited with blue locktite or it will shoot loose in about 100 rounds. I use a 22 brush to clean the loctite off threads where the rod goes through the unit and a brass "tooth brush" to clean the locktite off the rod when I disassemble it for cleaning.
I've got about 5,000 rounds through it and couldn't be more pleased. The Unit 1 is so accurate it deserves a target quality trigger.
I had a problem with one of the magazines but Marvel replaced it.
My Marvel shoots a little tighter groups than my 41 - You do have to count rounds while shooting because the slide doesn't stay open after the last round is fired by design - I count rounds so I don't drop the hammer on an empty chamber.
I can highly recommend the Marvel Unit 1 - I have no experience with the Unit 2.
Sounds like what I've already heard about the unit. I currently have a Kimber Target 1911 and just love the pistol. Trigger work has been done to this pistol and it shoots fine, so i thought with half the work already done, why not make a .22 shooter out of it. Glad to hear all the good reports about the Marvel. I too think it's a high priced unit, but this time I hope I get what I pay for.