A few people in my tri club have tried the Podium Legs/Air Relax and also the Normatecs. While they all prefer the Normatecs, they also say that for the price, the Air Relax does pretty much the same thing & are just as effective.
It seems that the biggest strike against the Air Relax is that it is the noisiest of the bunch. It's also a bit more bulky than the Normatec, but for $1,000 less, I can live with both. $400 is still a good chunk of change, so this is low on the priority list, but if someone wants to get me one, or if I receive an amazon gift cart to defer the cost, I may pick one up.