originally i too was thinking of getting smaller batteries. but now having stealthed twice with the 722 i'll go with the big batteries (i've got one and will order a 2nd).
its very nice having plenty of recording time, so you just don't have to worry about . also, glitches occur. my second time out when i "retrieved" my 722, i saw that somehow it had been powered up. not a problem with a big battery! with a small battery, you might have been worried that the partially discharged battery wouldn't be enough.
also the battery can be removed if security is especially tight. give it to another person, or throw it in your bag and if questioned, tell security its an extra battery for your laptop, mp3 player or whatever.