Thanks for the input, everyone. I ask because I've been looking at tanks and Pyramid Air is advertising extended life tanks for $400 that have to be recertified every 5 years and I spoke to the company that does the recertification in Denver and the cost is $400+/-. (Plus shipping.) PAir says the cost to recertify is about the same as a hydro and that didn't sound right to me. I was thinking maybe $50 to hydro, so I wasn't too far off. So, If you see these tanks, just know that the real cost at 5 years is another $400+ unless you are going to fill it with your own (or a buddies) compressor.
Cheers from Tulsa, OK,