You ask "Is it worth the extra money?"
I would suggest you price the batteries. 12 volt DEEP CYCLE batteries are starting to come down in price due to a new line of Golf Cars that runs on the higher voltage (36 volts instead of 18 IIRC) These use two banks of 3 12 volt batteries where as older ones use 2 banks of six volt.
However as of this typing you get the best "Bang for your buck" with six volt pairs, I've hinted at the reason
Companies that make batteries usually have several production lines. One line does nothing but golf car batteries, that's all it does, all year long it just does one battery, that's because there is that much demand for that kind of battery. NOTE that this may change in another decade or so as golf courses go to the higher power cars. but for now it holds true.
The other lines will produce different batteries, occasionally every day of the week, they are re-tooled (At great expense) and this expense has to be passed on or the company goes bust. Thus 12 volt batteries simply cost more.
This, is the primary reason I prefer six volt pairs.. COST is lower for the same amount of watts of power (Amp hours times volts)
There are other arguments too,, however they are arguments and often get heated..
And of course if you get a good sale on 12 volts.. You can do better there cost wise
Another consideration is that most six volt golf car batteries are very good quality to top quality, this is because the people who buy most of them (Golf courses) are looking at long term bottom line, They are also designed to be maintained by "hired help" which is good too. 12 volt batteries come in different quality rankings.. Some are designed for folks who look at the price tag only and wish to spend 30 bucks on a Piece of junk that is doing good if it outlasts it's 5 minutes or the end of the driveway warranty (And the installer will push if needed) Others are over a hundred bucks (For the same size battery) and need replacement every decade or so.
This is not to say you can not get a real good low-cost (I mean sometimes they goof and make a good one) or a real bad high cost (Same logic). But odds of a good battery are a lot, and I mean A LOT higher with Trojan than Excide