Nathan,
I don't think there is anything wrong with having the batteries in the laz, but it seems like they'd take up quite a bit of the space in there, and considering it is the only deck-accessible storage bin, I like having as much space in there as possible. We keep spare lines, fenders, a BBQ, paint/varnish, solvents, oil, antifreeze, cleaning supplies, 4 life jackets, a throwable, and an anchor rode marker! I would be really annoyed if I had to move all of that stuff just to check my batteries :/
Our alternative was to locate four 6-volt Trojan T-105s in a battery tray we built to go in the starboard battery area. We bought a watering system for the batteries, so all we have to do is plug a hose in (easily accessible from the cabin's access), pump the ball with the end in some distilled water, and the batts get filled to full (but not overfull). We also have a single Gp 31 starting battery to port.
You can see photos of our whole rewiring process from 2007 below. There are photos in there of the battery tray and stuff, although I don't think there are photos of all four batteries with the watering system. You can look waterers up on the net:
https://picasaweb.google.com/101945798606645671347/Rewiring
Just what works for us!
~Aaron