Yeah, I remember there was a debate about this maybe a year ago...at least several months back. You might want to do a search on that.
What was concluded...if I remember correctly...was that amodimethicone becomes water soluble with those two chemicals you included...but only when it's in the bottle...once applied to hair,it isn't water-soluble. That didn't really make a lot of sense to me, though.
I'm guessing the two chemicals makes it more water-soluble...much like PEG makes dimethicone more water-soluble. I think people have different experiences with what builds up in their hair...and they need to experiment for themselves.
I love to shampoo my hair (mostly with a non-sulfate shampoo, but I indulge once or twice a week with a sulfate), so I don't have problems with cones, generally. I just make sure I limit them to water-solubles, amodimethicone, cyclomethicone, phenyl trimethicone...but I can occasionally throw in a bad boy, like dimethicone, if I'm going to wash with a sulfate shampoo the next day.
There's an on-going discussion about whether cones like dimethicone can be washed out with a non-sulfate shampoo...I know this isn't what you're OP is about...but I somehow think they're related. At least in my own head...LOL.
I personally think build-up is so personal and individual. People need to find out for themselves and find a routine that works best for them...whether that's with/without sulfates, CO washing only, using certain kinds of cones, how often to wash, etc.
It makes sense, I promise. It's water dispersable in the bottle. Where it is combined with the other ingredient, and water. When you pour it on a surface, such as hair, the water evaporates and the cone dries into a film. Now
it's not water soluble.
The other thing I'm given to understand about these cones (amine-functionalized which includes both amodimethicone and bis-aminopropyl dimethicone) is that they will only form an extremely thin layer and not build up. Once on the hair, they will then repel other amine-functionalized cones from being able to build up.
I don't think they do the same for non-amine-functionalized cones though, so if you are adding other cones then bets are off.