I haven't ordered it from mt. baker, but I've used distilled water and a couple of vendors I use mix with VG and distilled water. Using a small amount of distilled water with VG helps thin it out for wicking. Using it as part of the ratio has a thin line for failure.. Too much water and you're actually exhaling water vapor(mostly).
The only real health benefits would be no PG if you have a sensitivity to it and so forth. VG can actually accent some throat hit of certain flavors, but that dissipates when you have a VG/H2O mix, practically eliminating it.
I would recommend getting pure VG and adding distilled water to your liking...if you end up adding the same amount that they would, cool. You can order that ratio next time, but I wouldn't gamble on ordering a bottle of it if you haven't tried it before...not because of the money wasted, but to me, waiting for liquid is worse than paying for it.