We're using the C&D Liberty Series...
http://www.cdstandbypower.com/product/battery/vrla/lib1000_12_373.html
2. Have you ever seem them provide 10 years of ACTIVE service in a UPS...
A Qualified Yes...
I've been to the facility that uses them (an Oil refinery in Indiana). After looking as some of the date codes (11 years), I'd have to say that they do last for 10 years. Now there were quite a few batteries that had a date code less than 10 years, most of them 8 years, but after talking with some of the maintenance folks, they're not able to remember failures too frequently (whatever that means).
Initially I was skeptical about any battery lasting longer than 5 years. After talking with the local rep and getting a better understanding of their product, as well as looking at a few date codes on the batteries on site, I've changed my opinion.
I'll have to say that I've never worked with flooded batteries, which by your post I'm guessing you advocate and have experience.
Most of the systems we work with have less than 100 amp hour requirements. The current project I'm involved with has anywhere from 1600 amp hours to 2000 amp hours requirements. The systems we work with have a 24 hour battery backup requirement, and in some cases 90 hours.
I'm a mechanical engineer, not an electrical engineer, so whether a 24 hour design task these UPS systems more than a 4 hour design, I can't comment. I'm guessing it has more to do with how many times they're discharged, and how far they're discharged. We disconnect the batteries when they fall below 18 volts, but I'm not sure how much that help.
Regards