Haven't communicated with you on a forum for a couple of years because I've been hanging out mostly on the "S" forums instead of O. Still have some O display pieces but sold off the O and replaced it with S. This is my 2nd venture into S as I did it once before around 2000/2001 but it didn't take. Don't get me wrong, O Scale 2R is great, but I wanted more than a switching layout and S allows me to do that. It is also large enough to build in for aging eyes and none of the smaller gauges are for me.
I think you'd like "S" and there is a lot more available than what you see on the surface. Most regular hobby shops don't carry much in the way of "S", but there are a lot that do and some who specialize in "S". You have to change your mindset from O to S. You'll find it on eBay or on the S gauge yardsale forum or just by asking for something on any of the S forums. I've seen S for sale on the OGR "For Sale" and "Wanted" forums too.
I don't agree with the statement above that there really isn't any size advantage modeling in S because there sure is. As you pointed out S is about 33% smaller than O so in any given space you will have more modeling and space to run trains in S......just like if you modeled in N or HO you'd have more space for running trains than in S. The beauty of S is you gain the operating space but can still see all the detail from a distance. And because the trains are smaller the same radius curve in S appears to be larger than O because the trains are smaller.
The smallest commercially available radius in S that I'm aware of is 15", then 18" and then 21" (SHS sectional track with roadbed). Using flex track I suppose you could go smaller, but why? The beauty of S or any smaller scale is you can have larger appearing curves which makes your equipment look better while running.
You can learn a great deal about S (at least S scale) on the S Sig Forum @ sscale.org. Lots of history covering AF up to present day, but mostly geared towards S scale rather than Hi-Rail. There is also a list of S suppliers which will give you a good idea what's available. And with Lionel and MTH jumping into S it will only get better.
All opinion of course but check it out.