Those bots are really just fancy phone trees.

That size 6 sable is a workhorse for watercolor, I definitely wouldn't have let it go for a full set of synthetics. I get the appeal of sharp edges for tiny details, but you're right, the spring is the whole game. Sable snaps back and holds a puddle of paint like a tiny water balloon, synthetics just dump it all at once. My fix is to load the brush way less and use a paper towel to wick off the excess before I touch the paper, that helps with the pooling, but it never feels the same. Honestly, you traded a tool that does everything for a set that only does a few things well. I'd try to track that person down and see if they're open to a swap back, maybe toss in a few tubes of paint to sweeten the deal. Sable is worth the hassle of replacing more often, you can't fake that feel.