The "experimental only" brake pads were from Barry Jay, I bought a set or two of them years ago.
As I recall, Rapco's were half the price of Clevelands, and Jay Barry pads were half the price of Rapcos.
They seemed to hold up OK.
Scuttlebutt is that Aircraft Spruce bought out Barry Jay, and discontinued their brake pads.
FWIW I just found an old post I made here back in 2008:
"
FWIW, I've got double-pucks on my 170. I have run both Cleveland & Rapco brake pads in the past. p/n 66-105. Had similar results with braking action (good), wear (OK) and lining dust (lots). Last time around, I bought a set of the "Barry Jay" brake pads that Aircraft Spruce sells: "not faa/pma,experimental use only". Brakes work fine, they're wearing like iron, and very little to no dust around the brake area.
Current Spruce pricing for 8 pads:
Clevelands $82.40
Rapco $44.95
Barry Jay $18.95
Seems like a win/win to me."
I bought an 8-pack of Rapco 66-105 pads recently from Spruce, cost about $50.
Their catalog price for a 4-pack of Cleveland 66-105's is $40-- so about 60% higher than Rapcos.
Do they give 60% longer life? Maybe, maybe not.
I see Grove sells 66-105 pads, $34 for a 4-pack.
So 36% more than Rapco's.
http://www.groveaircraft.com/brakepads.html