I also look for value in a battery, but I probably define value differently than most.
The Rolls flooded cell batteries we installed in our old boat (after fussing around swapping out the 8D's a few times) were still running strong the day we sold the boat, about 9 years after putting them in. When we replaced the batteries on our new (to us) boat, we stepped right up for two Rolls 8D. The initial price is pretty high. If you figure out that you will likely replace even a decent quality but lesser battery 2-3 times during the life of a Rolls and that as the years go by you will be (assuming your experience is like mine) a bit older, a bit weaker, and a bit less inclined to spend thousands of dollars at the chiropractor's you also save the cost of installation.
I see batteries with warranties as short as 24 months, and even then they are often prorated. If a 24-month prorated battery fails after a year, you only get half your money back when you buy another battery. Rolls are warranted for 10 years, and the first 7 of those years are a full-replacement, non prorated warranty.
Of course, if you tend to trade boats every couple of years it would be hard to recommend the Rolls. You will never get your money's worth out of them unless you keep the boat. I am not sure most buyers would pay more for a Rolls at resale time than for just a Sears Die Hard or K Mart special, as long as the batteries are working.