Finally I took some time to research on this and got myself a couple albums by the Impressions. I wanted to focus on Mayfield's earliest works, before Hendrix's 1967 album.
I've found those "typical" licks in the songs "I'm The One Who Loves You", "Gypsy Woman", "You've Come Home" and "As Long as you Love me" from The Impressions 1963 album (their debut, I believe). Mayfield was the lead singer and guitarist in the group. The songs must be available for a free listening in Youtube

A certain guitarist said "Hendrix was Mayfiled, only louder", what I've found to be an enourmous exaggeration. Many soul guitarists of the early 60's played in that style, using those major scale hammer-ons and pull-offs (Cropper, per example). Maybe Mayfield was the first to do that often in a soul record though. Usually these licks appear in the Impressions songs quite briefly, I mean, they are usually not up front and are quite short, you have to pay attention or you might miss them.

I'll start listening to their 3rd album now and I'll report what I find.