It's actually a fairly good way to test if your lab sucks ass. B/W is not forgiving to poorly calibrated equipment or chain stores that are cheaping out on replenishment.
small nitpick: RA-4 is a Kodak process. The Noritsu minilab I ran used Kodak chemicals. Fujitsu labs typically use a 'compatible' version of their own that can't be called RA-4. While the two systems work, we always found C-41 Fujifilm looked inferior printed on the Kodak processes and vice-versa.
The big problem with Frontiers was it was near impossible to fully eliminate the colour cast on B&W prints. You can kick the machine into B&W mode manually, but there are still limitations the RGB laser exposure engine and process puts on you. Practically that means you can't get a true black like you can with silver-halide processes.
They are still fabulous machines though. Awful user interface, but the technology behind them is pretty incredible.
However, the same skilled operator should be able to calibrate her minilab in order to obtain decent looking b&w prints on color-based paper (RA4 process - used by Noritsu & Fuji).