It has been a good 25 plus years, but I've handled around 70 cars with an RS-1, flat switching. A mixture of 55 and 90 ton tank cars, some MTs, some loads, some friction, some rollers, bad track.
The RS-1 weighs just about the same as the CF-7, and the TM's have similar current ratings. The extra 500 HP on the CF-7 would allow you to accelerate faster, although the Alco would load up faster.
FWIW, ATSF chose to wire the CF-7s just like a GP-7, with the "teaser circuit" excitation used in the switching mode. Working properly, a CF-7 (or GP-7) should load up fairly quickly. The other thing interesting is the transition; just like the GP-7 there is no field shunting. Series/parallel and full parallel is all you get.
I think ATSF really had their act together when they cooked up these things. (Well, that is up until they started using the "Topeka cab", also seen on rebuilt Geeps-)