I'm building a RR layout with an overall design of an O-72 loop close to 4 walls with another O-90 circle (with as much straight-run expansion as I can fit) inside that. The 2 loops will be connected at least twice, using 4 switches I have. For each loop, these are the widest curves I can reasonably fit. Of course I can always be unreasonable if I want to be, but only if it guides me to the best decision.
My switches are remote Gargraves rated O-72, and except for 6 short straight Gargraves terminal tracks, the rest is Gargraves 37" flex track.
Also, for purposes of the question below, I'm not interested in side or height clearances in this discussion, because they've been covered already in other topic threads I've read here. From those discussions I've already determined that my side clearances will always be wider than 3.5" from center rail, and height in tunnel run 6" above rails. So here I'm only interested in the rating of the turn radius, O-72 being a 36" radius.
Q: I'm running O-90 curves on the inside loop to get the least ridiculous (ie, best) appearances in what will inevitably, despite whatever straight I can fit in, be mostly a circle. But if I'm willing to compromise on appearances because O-72 is more convenient to build and live with...am I frustrating certain locomotive or rolling stock desires later in life that I cannot foresee now as I pour the concrete?
I am newly returning to model RRing, experience limited to being kid-in-the-70s with a few HO and O-27 starter train sets with tracks assembled on floors and the ping pong table. So now that I'm grown up, I can cut tunnels through my wall and design aerial RR spans for the cathedral space over my little kitchen...I wonder what kind of big brass or other heavy metal O-scale steam engines (or whatever else might be big...and same for cars) --what might I want someday that would make me say:
"Gee Whiz! I wish I'd built that run in O-90 after all! I thought I could run ANYTHING on O-72!!"
For example, should I swap out those 4 O-72 switches because, unless the inner circle only runs through them as straights, my otherwise O-90 inner loop will have those switch curves reduce the rating to O-72. Will I regret that when I want a big train later? I thought I could run ANYTHING on O-72!