As much as I'd like to agree w/you - I still feel that a tighter fit is an aid to consistent function.
The CZ manual appears to support that - IMHO.
On the fixed barrel/sights part....I honestly don't know.
My Ciener fixed sight conversion - seen below on a Kimber Target just edges out my Kadet. Not by much & not alll the time. I have to believe that's more because of the excellent trigger on the Kimber than anything else.
& those two nickled bad boys on the left and right will eat any Kadet out there for lunch - despite having the rear sights on the slide.
Another gun. legedary for it's accuracy - the Colt Woodsman also had the sights attached to the slide.
However......a common theme among pure target pistols seems to be the fixed sight/fixed barrel.
Bottom line would be - while I don't honestly know - I would tend to think you're right in that regard.