While I'd prefer to use "the solution", I still can't justify the price. I mix 1:3 minimum (concentrate to mixer), sometimes higher. I like to use larger glass tanks and have a few light puffs. I would go through "the solution" too quick for the cost. I would end up diluting it with pg anyway so I probably will stick with something like Holy Terps.
Actually, right now, I'm looking into bulk peg and pg, and pure terpene extractions so I can make my own 'Holy Terps'. I'd like to mix up separate AM and PM mixers with different terpene combos, try them out with my rosin, and if I can still taste any peg/pg, then I'd add a tiny bit of flavor (fruit, and herb).
Personally, after research, I don't really mind pg, vg, and peg for what they are. If they are the proper grade they are safe for low temp vaping. I just don't like the flavor of peg in particular, nor the others. I have found that mixing rosin instead of shatter helps make my mixes way more flavorful, but I still add concentrated flavors on top of that to get rid of the peg, pg, vg taste. I think, once you start mixing e-liquids past 1:1 you've lost your concentrate pure taste anyway. There's no flavorless substrate you can mix in that will really retain your concentrate flavor so you're always adding some kind of flavor after (either artificial, or terpene flavor, etc). So I'm not chasing that. I'm just trying to make a consistent, mellow e-liquid for day and night.
So ya, "the solution" is probably the best mixer for anyone that mixes under 1:1. And something like Holy Terps (or DIY: flavorless mixer as a base (ej, pm, ve) + Pan's Ink or Extract Consultants' pure terpenes + flavors) is the best option for anyone that mixes higher than 1:1.