I have not. But, given the 100% pure extract suggests using 1/80th of a teaspoon per serving... Be careful when mixing your base solution (in other words, leave yourself room to add more PG).
Be sure to note that the majority of what you'll find on Amazon are NOT 100% Stevia Leaf. Most are 95-99%, several listing seeds/stems/etc. For me, the distinction is important. YMMV. (There's a thread on here somewhere - search bar rocks! - that has a post I made not long ago before pulling the trigger, which contains a pic of the only one I found in St Louis which was 100%)
FWIW, I do get the bitter after taste you refer to when using certain other polysaccharides (Sweet-n-Low, Splenda, etc). To me (at least so far) there's just an intrinsic difference between those and Stevia. But, I have not tried a liquid Stevia yet (primarily because they always have other additives. If I want malic acid, etc... (and I'm sure as I progress, I'll use some of those too) I'll add it myself. (After having made a PG base for each as well).
More and more, the best part of DIY is, being able to make it EXACTLY as you want it!!