My previous job at the dealership, we only used PPG Envirobase. We started using it when it came out, we had as much experience with is as the PPG instructor. I worked with it almost on a daily basis. When we first started we hated it. But now, I don't hate it. It has it's ups and downs just like solvent borne. We were using it in a temperature controlled downdraft paint booth, first with handheld dryers on pedestals, later on fixed dryers set in the paint booth corners. I came to prefer using a single hand held dryer, as it caused less turbulence in the booth and had less dust, also I was able to concentrate on areas that took longer to dry.
Advantages: covers a lot better than solvent borne, metallics lay down a lot better, matches are better, it tends to be less aggressive on burn troughs (no solvent), single reducer required.
Disavantages: longer to dry even in ideal conditions, denibing is a little bit more tricky (but we get used to it with time), cost (maximum reduction is 30%, when compared to 100% to a solvent base), gun maintenance different (complete disassembly required after white base), more dust in paint (basecoat stays open longer and requires air movement to dry), color matching very difficult as paint color changes a lot when it dries, basecoat can't be catalysed.
They have a waterborne primer, it doesn't mix with hardener, it is only reduced with waterborne reducer. It is a DTM, it doesn't build a lot, but it is ready to sand in 30 min. air dry, very long pot life. It doesn't sand nicely. They also have a waterbourne clearcoat, my rep said it's only to have a complete line, they don't push it, it absolutely has to be baked to dry, never tried it or seen it in action.
Currently, I use only their basecoat when I know it's a tricky color (tri coats). I used it in a cross draft, and only have one hand held dryer, but I don't paint 4 cars a day, and I take my time. It requires some time to get used to it, and once that done, work comes out as good if not better than solvent borne.