Hi jomokins,
I don’t know of any specific comparative information about how Celsion (which as you mentioned is now called Talalay GL fast response) compares to Talatech blended Talalay (which is already one of the most breathable foam materials) but I would say the difference would be “slight” (which is how it is characterized on the Pure Latex Bliss site) and like most gel materials it would be more effective at the beginning of the night when you were first going to sleep than it would be once temperatures equalize when you have been on the mattress for a while.
Ventilation and moisture wicking is the most effective technology in terms of temperature regulation over the course of the night (which is why wool is a more effective temperature regulating material). Gel foam technology can add a slight secondary benefit but would not be a primary source of “cooling”. There is more about the factors that can affect sleeping temperature in post #2 here.
Sleep Like a Bear here sells Celsion (Talalay GL fast response) in 1" - 3" thicknesses and all sizes. KTT enterprises may not carry it in stock but should be able to order it for you if they don’t and some of the others listed in post #4 here may also be able to order it as a special order.
Phoenix