I recently switched from SMURFF to RF as the cost of a simple orbit-capable rocket went to over 80k Spesos with multiple Asparagus stages and what not. Barely reached the magic 10k dV mark with it. Now I came back to RF (played with it in Stock but got annoyed of the ullage necessity and RT). It looks okay with the Stockalike configs and the realistic mass set to false. My design for an orbiter went from a behemoth with like a million stages to a single shape, 4 engine powered rocket and three stages for 14k Spesos. So my point is yes, the Stockalike config is correct for RSS too but I havent tried any Earth - Jupiter - Pluto windows yet, they might get a bit tricky, especially with RT installed.
If you feel still unsecure, you can change the mass of the non-engine-related parts by 25% to compensate. RF is only tweaking the mass of tanks & engines. Thrust aso is still the same afaik.