Thats a pretty succinct rule of thumb for warm water, I'd say.nadwidny:"...unless you're doing huge exposures or steel doubles, you don't need a drysuit".
(On the other hand, if you plan to do two fairly deep dives involving any sort of overhead you basically have two backgas options. Either bring two sets of aluminum 80s onto the boat, or take one set of aluminum 80s and use a slung stage 80 on one of the two dives... FWIW YMMV)