[TPIN] 13A4A question

[sklingel at comcast.net]

Someone a few days ago mentioned they were trying to find a happy medium between a 3C and a 13A4A I believe. It seems to me there's a world of difference between the two. On my own great mouthpiece search (mainly on Schilkes, due to J.Donaldson's advice -good quality, consistent, and reasonably priced) concluded with a satisfying settling-on of a 12B4.
I tried a bunch from a 9C4 to a 15C4.  I could NOT believe the difference between a 14A4A (which I like) and the little golf-tee-with-a-hole 13A4A. (I'll expect a few smart-a answers here:), but is it me and/or my embouchure, or does anyone else find the 13A4A almost unplayable? I can only imagine what a 6A4 is like. (And yes, I do like the feel of the Schilke 4 rim, in case you noticed.)

Steve (just curious) Klingel