The 12v batteries have always been specified as not a good in cycling as the GC batteries, and many folks have found that to be very true.
Trojan has been messing around with their site a lot lately, so I pop in once in a while to see what they are doing this time. They have come up with a nice listing of the top end of their line, including some 12v batteries, most of which are shown to be lower than the GC or other "real" batteries.
Nice that they list the cycle life for a change rather "longer, better, higher quality" type terms that mean little.
There are 3 12v batteries in the 1200 cycle at 50% discharge section, which is as good as it gets. Of interest is the J150
150AH at 20 hour rate, 1200 cycles at 50%, about the same size as a gp31 but about 1" taller. This could be a very good battery for those that currently have a single battery setup as you would get some very good specs with much less modification than trying to squeeze in two batteries. I would expect it to outperform pretty much any other 12v in the same size footprint, and last double even the other Trojans.
Also interesting is that the old standard Trojan SCS200, like we have, is no longer listed with the other true deep cycle batteries, but shows up in the marine/rv deep cycle starting batteries.