All my railroad is R1 including switches.
For sure I don't care about the overhang on the R1 curves, especially with very long rolling stock.
I have an LGB UINTAH which can go everywhere on my railroad.
Then I have USA trains Alco S4, GP38-2 & GP7 all run fine on my railways.
However I cannot buy an USA trains SD 70, I think she might run on the ralroad but would not be able to draw wagons (they would be pushed away from the ralway).
Also as my layout is having two side walls with a limited space between walls and track on its sides, thus this loco SD70 would knock the walls.
I have also Bachmann 4 6 0, yes they run on R1 but in some areas of may railroad it is risky !
Speaking about Bachmann I would like to know if the situation for the new DASH9 is the same as for the SD70.
The drawback of the SD70 is that the vertical truck axle is not in the middle of the truck but pushed back toward the truck rear.
This create this large overhang on R1.
Running a Dash 9 without any wagon would be my pleasure, but I don't currently know what is the engine nose overhang on an R1.