Purchased a new to me R9 (R18xx) from a forum member, and found a stainless relatively new but used lightly Solo at a gunshow...both to the range today:
R9: This one has had one prior range trip and loved Lawman and Gold Dot 124. This time it ate 13 rounds of Lawman 124gr; 13 rounds of Gold Dot 124; 6 rounds of Federal premium 124; 13 rounds of Black Hills subsonic 147 FMJ...all went "bang" with no issues. I used the one mag that came with the pistol.
Solo: Multiple jams (failure to extract cleanly) with FMJ (Lawman and with Black Hills), more with one of the mags than with the other. One mag liked the Gold Dot 124, with one jam that I attributed to limp wrist. The other mags didn't do as well (the same one that was a problem before). The good mag liked the 7 rounds of Federal that I had left to shoot. I will ask Kimber to replace the questionable mag if they will.
R9 vs Solo: R9 recoil was, as usual, very brisk...my arthritic wrist noticed it after a few mags! Nevertheless, it required less of a death grip than the solo, which had a more gentle recoil but required a much tighter grip and stiffer wrist to function. Interestingly, the Solo was less likely to jam with one hand shooting, while my R9's do better with two hands on the wheel. The Solo sight picture was a quantum better than the R9, with impressive accuracy at 7 to 12 yards vs the R9, which was close until I started to flinch due to painful wrist joint. The Solo was more fun to shoot but is not yet trustworthy as a carry piece. The stainless Solo is really very "pretty" while the R9 looks functional and solid. The new R9 is almost ready to carry, but needs another 50 rounds through it before I'll do so. Meanwhile the trusty Covert remains in my pocket at nearly all times...and it just looks black and deadly (as a covert carry piece should look).
Life is good!
John