I have a Marvel that I use for Bullseye matches. The accuracy is excellent and it handles most std velocity stuff, no problem. The one disadvantage is that the slide does not lock back on the last shot since it is aluminum and not steel. Advantage Arms (in conjunction with Marvel) has a unit where the slide does lock back. Accuracy is excellent and I've heard their magazines work better than the Colt Ace type, but I have not tried them yet.
I have heard bad things about Ciener's customer service. They've been in the conversion business a long time but that would be a drawback for me.
I also have a Colt .22 converison unit that I use occasionally. Accuracy is very good. The only drawback is that because of the floating chamber you NEED to use plated .22s, otherwise the floating chamber will lead up and it's a real PAIN to get it un-stuck. The Colt does lock back on the last shot since the slide is steel.
I do not have any first hand experience with the Kimber unit. I've heard they're okay and the price is reasonalble. I use one of their mags with my Marvel unit but it doesn't always work feeding the second round, so I only use it for practice and not matches.
I bought a used silver color ciener at a gun show a few years ago for my 1911 for $115 and have nothing bad to say about it. It cycles and ejects all walmart cheapy .22s as well higher quality ammo and accuracy is at least average to very good depending on ammo. Since I have not needed warranty work I don't know what trouble I have been spared. At the last gun show I bought a chiappa 1911 .22 and hear it needs a few hundred rounds to break it in, I had numerous failures to feed but as more rounds were fired it failed fewer times.
I have two Kimber units, and they have both proven accurate and reliable. But if I was interested in bulls-eye competition shooting standard velocity ammo, I'd go Marvel.