Atlas switch machines will run off AC or DC since all they are is a coil of wire at each end of the plunger to attract it by magnetism when the coil is powered. A coil of wire is not polarity dependent and does not care whether it is fed AC or DC as long as the current does not exceed what the coil can handle. They will activate quicker on AC simple because the AC terminals provide 16V where the fixed DC only provides 12V. Basic electricity - more voltage applied to the same coil produces a stronger magnetic field.
I have always used Atlas & Peco switch machines wired through a capacitor discharge circuit which gives a good jolt of AC to the coils and don't run contacts for signals or other auxiliaries off them.
Lobuc Valley RR
"The Hobo Route"