I agree - not good for concealed carry. And I do not want to get used to the extension at the range and then not have them during a high stress situation.I have and they are great for the range, but i do not carry with them.
Not to thread jack but like the holster who makes them?To answer your question, NO I have not done exactly that.
I do have Pearce extensions on both a XDS 45, and an XD(m) Compact 9mm.
I like them on both guns.
They're relatively inexpensive. So buy a couple to see if YOU like them.