I'm certainly no expert, but FWIW; my MRC O27 is capable of running my (few) PW locos at a much lower starting speed than the PW transformers I have. It (the MRC) actually starts at "0", as opposed to the 5 volts or so my PWs kick in at. I especially notice an improvement with PW American Flyer...
I can only assume that other MRC items for AC would work (at least) as well...
Hope that helps (a little)
Mark in Oregon