I haven't tried the cool bed III. What we use is a "Pacific Plush Pet Bed". It doesn't use water, but it has a flax seed filler and can be chilled in the freezer, or heated in a microwave. My dog has had one for just over a year, and he loves it! It's great because if we're going to the beach for a picnic, we just put it in a plastic bag and stick it in the cooler with our lunch. It keeps Pepsi, (our dog), nice and cool. In the late Fall and Winter, we just "nuke" it for about 4 minutes, and it keeps him comfortable for hours!
I also like the fact that the cover's made if "minkie chinelle",(forgive me if I mis-spelled it), on top. It feels like a soft velvet.The bottom is nylon, so it just wipes clean. Best of all, it's is removable and machine washable. The bag inside is made of a material they call a "ballistic nylon", and hasn't punctured, or ripped!
Is there anyone else who has one of these? We had bought ours at a trade show last year and they said that they were going to sell them in ebay in 2007. I hope they did, because I think it's something that would really fly! Sorry if I sound like an infomercial, but this is one of the most practical things I ever got for our Pepsi!