After finishing off a dry bale of Sunshine #1 today, I think I agree on the value of presoaking. At the very least it will cut down on the dust. I didn't really notice any problems with water uptake of the dry mix, but that could be due to a difference in surfactants in the Sunshine vs. the Pro-Mix. The perlite tended to float to the top, which isn't particularly attractive. I do think presoaking should increase the volume of the mix for better economy. I got about 90 1-trade-gallon pots out of 1 dry 3.8 cu.ft. bale, which is about what one would expect from the Premier Tech calculator. Next bale I'm going to presoak and see if I can fill more pots.
BTW, from my vendor, the Sunshine #1 mix is $30.53/3.8 cu.ft. bale, basically the same as the BX.