I disagree. I think thicker ones definitely retain heat better--and they "die" after 3 years just like the cheap ones.

I've had opaque-blue-on-top-black underneath, transparent blue and clear. They all last maxium 3 years and the warranty isn't worth a bucket of backwashed water. It's only if it de-laminates, not if all the bubbles all fall off in your pool.

I went from an expensive diamond 17mil clear to a blue transparent 12mil for just that reason--I'd rather spend $120 than $220 for a cover that will last 3 years.

But a good reel is definitely worth it. I had one of those plastic ones and the bearings even were plastic. They tore up and made it nearly impossible to turn. Now I have a metal one with steel bearings and, in its third season, it's like it's brand new.