Big steam definitely likes big curves. And I think newer stuff is more sensitive than the older USH and MG brass.
I do have a fairly new 10-coupled PRR N1 from Sunset 3rd rail last run. It has no problem with 52 inch on my main and will also handle 48 inch on my branch. All wheels are flanged. I have an old MG 2-10-4 (PRR J1) and it does like 52 inch, even with blind center drivers. It goes around, but under protest and again, no kinks.
I have also run a recent Sunset N&W Y3 (or Y6) that belonged to a friend. It easily handled 48 inch radius but as you say, quite an overhang.
As for Large curves, I could have build a loop with very large curves in my 23x47 space. But my primary running interest is operations. I don't get much from just seeing them run around. I like to switch industries and make up trains following a pattern. I have switchlist generator that tells me where the cars go, and then I and my buddies run the RR to deliver them.
