Which dedicated .22 AR upper/complete gun did you buy and why?

[rob_s]

Known complete uppers:
CMMG
Model 1 Sales
Spike's Tactical
Tactical Solutions

Known complete guns:
Colt/Umarex M4 Carbine .22 Tactical Rimfire
Smith & Wesson M&P15-22 and threaded barrel model


What I want to know is:

1. what made you choose one over the other?
2. what were your experiences with either/both prior to purchase?
3. what were your initial impressions?
4. what, if any, break-in issues did you have?
5. what, if any, initial tinkering did you have to do to get it to work?
6. what's your current round count up to?
7. how many malfunctions have you had to date and has the frequency increased or decreased?
8. what is your current impression of your purchase?
9. do you wish you had bought a different make/model now that you've been shooting it for awhile?
10. what ammo has been the *best* (most reliable and accurate) in your upper?

what I am NOT interested in hearing about are .22 drop-in kits on 5.56 upper and I am NOT interested in hearing about out-of-production uppers like the DPMS. I am also not interested in hearing bashing of one or the other, or hysterical responses/defenses if you feel like your choice is being slighted. Finally, while I'm not opposed to hearing about it, I'm not terribly interested in the Carbon 15 .22 upper or in the complete guns like the Umarex or the S&W dedicated .22 ARs. Complete, dedicated .22 uppers only.