Well, I know many people don't care about using sights on a gun for self defense. However, I prefer aimed fire (especially with a pocket pistol where it is easy enough to miss as it is combined with the very low magazine capacity.) And, I have not found any night sights released for the Beretta Nano yet.
I was interested in the Kimber Solo until I heard that it had reliability issues, it still doesn't have night sights available for it, and they seem to be making them at a rate slower than molasses.
As far as subcompact 9mms that are in my sights for my next purchase right now. The Sig 938 takes the cake. Night sights, 1911 trigger, ambidextrous safety, and 7+1 if you get the "extreme" version (other versions are 6+1).
If Kimber fixes the Solo and someone starts producing decent night sights for it, that might take the lead over the Sig. The fact that the Nano has no safety turns me off.
If I don't want to forget to flick the safety off, I can just leave it off and keep it in a holster. However, these are "pocket pistols" and I don't think it is too wise to have a these guys in your pocket without the safety on (IMHO).
Rifle: Custom AR-15, Tavor, Arsenal SGL 31-68
Pistols: Colt Python, XD(M) 4.5" .40, Glock 19, M&P 9mm, Walther PPQ 9mm, HK P30S 9mm, Walther PPS 9mm, Browning Buck Mark