I recently settled on a two-tone Sig P290RS. Paid $493, shipped, from FIREARMS4YOU(sp?).
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The Solo is a nice looking gun. It seems that it wasn't meant to be shot allot, and tears itself apart. Much like the Rorbaugh and Diamondback. I have no use for a gun like that.
The Kahr is a tested and proved design. Their polymer guns have never felt good in my hands, though. If it fits you, I'd say it's a viable option. I think it's the "Yard Stick" by which to compare this class of gun.
I really like the Sig P938. However, one of the features I wanted for this type of gun is smooth and snag free.
The Shield is great, good price too, of you can find one. Just a bit bigger than I want.
The KelTec? Had one, never again!
I'm glad I settled on the P290RS. It's at the heavy side for one of these sub-micro-compact-itty-bitty nines. This helps make it very shootable. It is not to heavy for pocket carry but, doesn't hurt your hand to put a couple hundred consecutive rounds through.
I've put 200rds of various FMJ, 80rds Gold Dot Short Barrel, and 200rds of my handloads through (125gr TC Moly-coat lead from Bear Creek Supply). Not a single problem, no issues.
The trigger on the RS (ReSet) variant is very much like a double action revolver, only a bit lighter. I've been carrying snubs for years, so it is an easy transition.
It's sturdy, shoots bigger than it is, and conceals smaller than it shoots. I like it!