I had my layout built to allow operating of either scale or high rail equipment. The MTH .138 tall rail is the smallest that will run high rail. All turnouts are #5, #6 or #8 handlaid and tested with both kinds of wheels.
I made three other somewhat limiting decisions. These were #1, oversize couplers rather than Kadees, #2, Legacy rather than DCC, and #3, a 30” minimum radius rather than 36” to 40” minimum.
I have some AM scale wheel engines and passenger cars with scale wheels and they run fine. I never tried a RR Berkshire, I doubt it will navigate the 30” radius curves.