Funny thread.
One can pretentd that group 27s of many moons ago were deep cycle, and that th group 27s of today are dual purpose, but the only likely difference is the sticker, and the mnarketing department that decided term X vs term Y would yield X amount more profit
True deep cycle in the group 27 size? Even trojans group 27 is rated at only half the cycles of the T-1275/J 150.
Does not matter at 18 cycles a year though, either way. The charging and float voltage, if left plugged in, would have more of an effect on longevity than whether one buys wally worlds cheapest 27 or trojans top quality marine/deep cycle.
Those cycling deep hard and heavy and can recharge properly, promptly and fully, can realize the benefits from actual deep cycle construction. at 18 cycles per year and only a few years expected, you can get a starting battery and carry 10 less pounds there and back every few years.
http://www.pbase.com/mainecruising/deep_cycle_battery&page=1
