> This place in Santa Ana, with a website, http://www.powertron.com told me over the phone
> that I would be better off with two 6 volt golf cart batteries wired in series than two 100 amp
> hour batteries (such as their 27mtx) wired in parallel...

Yup. Two twelves in parallel will invariably end up in slightly
different states of charge with respect to one another. That means
they'll essentially be "fighting" each other just sitting there under
the seat, slowly wearing themselves out. Two sixes in series are more
"cooperative".

--
John Bange
'90 Vanagon - "Geldsauger"