Ditto on the shorter life of Gold. that may not be entirely the battery's fault, however, as the newer vehicles are not as battery-friendly.
I've bought several of the AGMs and have not had any fail yet. But, all are under the 5 yr mark.
The last Gold I bought made it just outside of three years, and received the occassional finishing charge, and was in a battery-friendly older vehicle. They refused the warranty it because the new warranty has changed, even though technically it should have been honored by the policy in effect at purchase. It was no longer mine at that time and the new owner let it go.
-m