Yeah, prefer current control over voltage. I had a constant current run that ran from 6.5 to 8.8 volts on the meter. I think the ratio of cathode area to anode (part) surface may alter the voltage some. I've messed around with my acid concentrations and couldn't find a big distinction as much as new acid needs more voltage (which matched up with the idea of "breaking in a tank").
Caswell says lower current densities get larger pore sizes, but with a softer layer (fewer pores would be weaker). I used to try to track my current on a constant voltage setup, and I would exceed 12 A/sqft pretty often. It always puzzled me that some Rit dyes would work and others wouldn't. Apparently, the pore size was too small for some of the pigments.
I had to study my new supply a bit. The translated chinese instructions were not too clear. It has a current limit knob and a voltage limit knob. They both operate full time and the two LEDs tell you which limit you are hitting. I usually just crank the voltage limit well above the initial voltage and set the current for the density I need. It has been a big improvement on coloring and you can watch the voltage swing up and back down.
I've done a few splashes, but I think this winter (when it is not hot) I will try using my old airbrush for some sort of effect, if it beats an old toothbrush splatter.