The Pebble Polymer has better air flow then the ones with a material cover.The AirHawk, is no good on a ? ***** Pad ? like on the back of a rebel.
also the AirHawk adds a fair bit of height, to an already precarious seat.
For long journeys, there is only one answer, re design the whole seat.
Ok for not so far's, then yes I would also go with the smallest of the ButtBuffer pads.
They stick well to the substrate, and are filled with dense goop, so they probably only add about 10 mm to the existing seat.
I have a short legged woman, and she is happy with the ButtBuffer.
We tried Sheepskin, but its marginally better than the factory seat, and takes days, to dry, after a thunderstorm.
OK, I just checked their web site, and its a bit messed up now.
Back when I bought mine, they had a page that showed the different sizes, but also, back then there was only one !
Dunno wot that pebble dash is, but if they went back to the early page, where folk could see the different sizes, on actual saddles, it would help a lot.