Re: Battery Sizing - am I crazy?
The "maintenance free" caps are often welded or otherwise secured down. There may be extra electrolyte, etc. to compensate a bit but the whole idea was "we can make it good enough so you never have to add water". Mainly for the crowd who find tire pressure and oil are also things too messy to do themselves.
Your local stores do carry falt-plate AGM batteries, from all the leading makers. They're almost impossible to spot even if they are on the shelf, but you can always as the clerk, or go right to the local battery distributor. Of course AGM isn't perfect either but that's a whole other debate. They'll be priced about halfway between the Optima and conentional wet lead.
Or of course you can stay with the MF battery and just make sure it needs replacement inside the warranty period. (G)