The tartness is fine IMO. Honestly I was pleasantly surprised at how close the flavor is to a natural taste rater than a candy taste.
Selling pre-steeped juice is a great ideal. Especially for the flavors that are very blah at the beginning of their life cycle. I think a lot of juices get bad reviews from newer vapers that still do not understand the importance of steeping. So if those flavors are sold after letting them steep then people will be getting a more true to flavor juice. It is also going to appeal to seasoned vapers, especially for those of us who like a juice and forget to reorder so that we always have some that is steeped and ready to go.
As far as PG/VG percentages go....well it does not really matter to me. I no longer care all that much about throat hit, nor do I care about blowing huge clouds. I am 100% about the flavor. TBH with all the RBA's out now with adjustable air flow wicking is not so much of a problem anymore. So even if a juice is as thick as syrup I just close the air flow thus creating a tighter draw and as a result thicker juices are pulled to the wick.
I fully agree with Carolina's thoughts regarding pre-steeped juices. Catering to the hobbyist crowd is one thing--we understand the need for steeping and will often have a bunch of flavors sitting in boxes/drawers all waiting for the pleasure of our vape. But many people just want a juice they can vape right away. Case in point is a friend of mine. He's the type that could easily go hobbyist but chooses not to because he already has so many other things going on. He just wants a vape that he can take around from site to site and not have to fuss too much about. So he has a pair of evods that he uses on top of his spinner and keeps one or two bottles of juice on-hand that he picks up at a local B&M. He'll change flavors from time to time, but that's about it. If he were to pick up some GTV, he'd crack it open right away and probably be disappointed.
I use tanks, both with airflow controllers and without, and have never had a problem with "All VG" juices. Of course, as you said RML, it's never truly 100% VG, but the point still stands.