I fear we stray from the OP's topic, and should probably start a new thread on this.
Reddog1 RV list> Thank you for that information. I've never subscribed to the dogma that RV manufacturers only put out what's best for the consumer. My observation is that the vast majority of them sell what's convenient and inexpensive. That's why a huge amount of the posts on these forums are about modifying the RV's we have to be better.
The reality is that this list is basically hearsay, and lacks electrical facts.
Here's a little video explaining why 6v are better...but only by about 6%>
http://www.youtube.com/watch?v=tGNMenyNqwUWhat the video doesn't address is that golf cart batteries will take a 50% discharge hundreds of times more than most (maybe all?) 12v deep cycle batteries due to their thicker plates.
My personal experience bears out this 50% discharge superiority. I will admit surprise that the GC batteries are only 6% better in available power, as anecdotally it seems much more to me, but I defer to science on this.
To each his own. I'm more than content with my battery choice, and am pleased that the rest of you are content with yours.