No, I haven't written between the two --- it's a bit superfluous in my opinion; in general, with the 4.A, you get the benefits of the custom fit, which are not to be diminished. Basically, isolation improves, comfort improves (though the 4.Ai is very comfortable already), and insertion depth improves. Insertion depth, along with isolation, can improve things quite a bit, namely with regard to vocal body, bass/treble extension, detail retrieval, and overall cohesion. I've commented before about the differences between the 4.A and the 4.Ai on this thread before and perhaps in other threads, but you'll have to go digging for them.
I already read all of them, actually. I was more interested in 4.A vs 334, than 4.A vs 4.AI; but from your description, it seems you would give the edge to 334.