Has anyone tried using a dried solvent and had better results? One would think that the less water the better, but would there be much benefit in a 1% difference in water content?

You haven't mentioned what the solvent is for but think about it this way you will be shaking/swirling your dried solvent with what swim assumes is an aqueous solution full of freebase spice + NaOH. The solvent will absorb water from the solution (which is 99%+ water) so its fairly pointless.

Water is a polar solvent so it can dissolve in other polars making a solution but also attaches to salts too. I think you need to give water energy (initiate it) to make salts dissolve into it, so it is marginally OK to have some present in freeze or long medium-temperature evaporations