PX15,
Night sights aren't much different than any other during daytime shooting. In fact, some brands can be less visible than normal three-dot sights, since the "dot" isn't solid, but rather a ring.
Personally, I only put night-sights on guns I fully INTEND to use as defensive guns in a MAJOR way. Right now, that means I've only got two guns so equipped at present... a Les Baer 1911, and a Glock 30 .45. These I consider primary "battle pistols", to be used under any and all circumstances. My other pistols that DID have night sights have had them swapped out for adjustables.
With a pistol like the P-11, where it's use is more limited in scope, I believe night sights would be necessary only if you really, really wanted them. The standard sights should do just fine, and somewhere there's a paint that'll stay on that front sight!
Re the slide stop: It's pretty much intended to be stiff, and not used as a thumb release at all. Standard practice is to simply retract the slide and release, rather than thumb the release. It will loosen up over time and become usable as a thumb release, however, or you can always take some fine sandpaper to it and the accompanying slide groove and loosen it up yourself.
Flyer