So no big issues, just a thought that if the custom shop uses rough maybe the production model would benfit fro it.
Let's share what came to my mind, FWIW.
Smooth magnets are more consistent in their actual dimensions and surface texture. Therefore they are easier/faster to mount and aren't subject to cause mechanical/vibrational problems met with some RC bars.
Anyway and once again (sorry to ramble), RC bars are not equal: depending on their age and on their batch / production process / the foundry where they come from, they can exhibit rather variable specs for a supposedly "same" alloy : actual mass defining the measured inductance, surface oxidization affecting eddie currents or not, inconsistent charge from magnet to magnet and even along the sides of a single bar (most magnets reveal to be inconsistently charged on their whole length when one measures them with a gaussmeter / teslameter but it's even truer with RC magnets IME).
For these reasons, mounting "a" rough cast bar doesn't guarantee what it will give sonically: in some cases, it makes a clear difference compared to a stock smooth magnet. in other situations, it makes no differences or not enough to be worth the hassle.
For those who haven't lab gear at disposal, the best thing to do IMHO and IME remains to try various magnets until the pickup sounds right, regardless of which kind of bar is used and even regardless of the alloy
meant to be tried (knowing that a bar sold as an "A2" or "A3" might actually be made of another compound than claimed by the vendor, for whatever reason).
This approach is even applied by boutique winders AFAIK: I clearly recall a set of Stephens Design P.A.F. clones whose PU's weren't hosting the same kinds of magnets - there was a smooth shiny bar in the neck model and a dark RC one in the bridge unit.
