You're probably right with regard to the rigid being the way to go. However, I find myself strangely drawn to collapsible lenses. I've got a nice uncoated Elmar nickel 5cm, and a Konica 50/2.4 that was put out in 1999 (?). That one's a planar design, so very sharp. I'm missing a collapsible sonnar, and as I doubt I'll ever see a CZ Jena (that's not faked)...
Sadly, these collapsible Nikkors are no longer cheap!
I too like the collapsibles. I had a Fuji Cristar a while back, which is pretty rare, probably rarer than the Nikkor. Seemed to render exactly like a Summitar.
Currently my LTM collapsibles include the Nikkor, Summitar (uncoated), Summicron (early radioactive) and Elmar. Would like to get a collapsible Canon Serenar...and a Nikkor 50/3.5, but would need to be really lucky to nab one of those.
Here is a thread listing a bunch of other rare 50/2 collapsibles in Leica screw mount:
https://rangefinderforum.com/forums/showthread.php?postid=2735820