Did this painting a few days ago in a little 7x10 sketchbook trying out how these paints work. I coated the paper with the Binder medium before starting. Even so the paints dried fast enough I only noticed a small difference between them and standard acrylics. Misting helped a bit but I was having to stop to do it every 3 - 4 minutes.
The addition of Slow Medium (aka retarder) slowed their drying time similarly to my routine of conventional acrylics and retarder. I didn't notice any difference between Interactives + Slow Medium and conventional acrylics + retarder. I'm still trying to work out if there's a better ratio of retarder to Interactives that will extend their wet time to the same extent as Golden Open.
I used the unlocking formula too and I admit it was fun being able to go back and rework an area. However, I am not completely comfortable with the idea. I worry about the use of any alcohol based solvent on acrylics. I have concerns that it weakens the paint binder and compromises it's longer term archival abilities.
Of course I'm sure Interactives fast drying even with slow medium (same with standard acrylics) is because I live in a part of the country where the average daily temps around this time of year is usually 98 - 101 F. (36.6 - 38.3 Celsius)
I gave up trying to blend them wet-in-wet oil painting style and just treated them like my standard acrylics. It may be at cooler times of the year I'll see a noticeable improvement in their open time and blendability. I'm sure atmospheric conditions plus the kind of surface used have a big effect on how any acrylic behaves.
So far, of the two new kinds of acrylics I've tried (both of which I like and enjoy) I prefer Golden Opens. They stay wet for a long time even in the heat and blend more like oil paints. All without needing to use retarder - which is necessary for my style of painting with both Interactives and standard acrylics.