Just wondering which I should zero in on, feel free to post opinions on better seats if you feel a better option exists.
Nimbus slim for the win!
I guess it all comes down to how much padding you like and if you like vinyl or not. The slim is slightly, slightly less padded than the street, but at the same time it doesn’t have the vinyl cover so it’s not great for sitting on for a great deal of time. Pretty much comes down to personal prefrence between those two main differences.
I have a Kh street and a Kh slim and the slim has a better feel in your hand for sif but street is better on your sit bones
Impact Naomi with CF base thinner and lighter than both of them 
As Knoxi said thinner saddle are easier to grab for SIF etc and a vinyl cover makes it easier to pull the saddle out and slide around on it.
For trials your should be rarely sitting down so the thinner and narrower the saddle the better to keep it out the way.
I have used all the aforementioned saddle and keep coming abck to the Naomi for all the different riding styles (you do need to upgrade to the CF base though as stock it has the weaker nutted base that snaps)
If it’s for trial, then you should definitely go for the Slim saddle. You will have better grip seat out, which is what you want for anything that is trial seat out. You don’t sit much on the saddle if you’re doing trials…
Can anyone comment on differences between the Naomi and KH slim? This would be used for trials/flat.
I want to replace my Fusion on my kh20 with something with a smaller profile. I like the Naomi on my Impact, but I’m not to fond of the interface between the seat and the post.
Does anybody have both and can they compare experiences?
I don’t have either but the Naomi is definitely thinner.