Just trailing the rio system at the moment and I'm mostly impressed. I found the PC system quite transparent, not all bad but can cause problems here and there.
Both systems very nice to print with being a nice short creamy ink. The opacity of the rio over PC gives it an edge in printibility for me personally and my uses. The selection of bases available with the PC system is unbeatable, I used either the Amazing base or started with clear SSVFF, so a terrific solution for those wanting variety in ink uses and not having to carry a bunch of different systems.
I mix in small quantities. 300-500 grams so PC obviously a little touchy and sensitive when mixing to formula. Unlike a regular pre mix system which is a little more forgiving.
Either way I love the Wilflex IMS 3.0. The UI, the features of it, printing a nice little label with the formula to stick on my ink pots.