In real life, huge great batteries were directly conected, but only when it was certain that the voltages were as near as possible the same. In normal service, they floated in parallel, but were separated for routine cycling which was done as much as anything else to check that the intended capacity was actually there. The cycling was very, very manual ("More power, Igor" style switches), with a traditional bit of panic about the back end of Friday.
A herd of SLA batteries should be no different, repeating the importance of checking that the voltage of each is the same as that of its mates.
Any differences will be averaged, so poor batteries will gain a bit of false voltage at the expence of the good ones. When connected in parallel, I would anticipate the use of a nice dumb trickle charger, rather than anything smart and sudden.
Daves link is a good illustration of the need to consider evening out the distribution wiring resistances.
re colins comment - "ex" is roughly the Latin for "has been", - "spert" is late Anglo saxon for "drip under presuure". So a good call.