The stated max load is 400 lbs. I'm pretty confident that it could hold that and more and still remain stable. The heaviest I've had mine loaded out to is:
Me 225#
Milk crate with 3 gallons of water in the bait tank and tackle 40# +or-
Batteries for fishfinder and bait tank (12v 7 ah x 2) 10# +or-
5 lobster hoops 25#
Food drinks etc 5#
Fishfinder and UHF radio 5#
misc crap 5-10#
Rough total 320# (error on the light side, ask Paul, he's helped me haul the loaded yak down the steps at LJ--sorry Paul).
The Hobie Adventure has a 350# rated capacity, it may not be my first choice for a dive platform. I plan on using my Outback for diving this spring and summer and have no doubt that it can hold all of my gear and and fish that end up on the pointy end of my spear
.
What ever platform you choose, make sure you have no problem getting yourself back into the boat after your dive. Outback is very wide and stable but it can still be tricky getting back in (inflate your bc and take it off first).
Steve