I have a Brownies 390. While you might expect it could put 3 divers to 90 feet by the name, it can put 2 normal/reasonably good divers to 70 feet, and 3 EXCEPTIONAL divers to 60 feet.
I got the Brownie for the bahamas, where there is a huge volume of diving between 25 feet and 50 feet deep, which is excellent for the Brownie...along with the lack of current we have in palm Beach, Fl where I live. I have used the Brownie on Horseshoe Reef and many of the Boynton and Delray reefs, and it works well as long as there is no screaming current running at a 45 degree angle to the reef ( sometimes you get blown off the backside of the reefs by an outgoing current--Gulfstream eddy or whatever...This can be a 2mph current, which is easily defeatable with scuba tanks by getting close to the bottom, out of the main pull of the current, but it makes Brownie divers work much harder than scuba divers that know how to do this. If there is no current to speak of, there is probaly less drag with the brownie from just normal swimming--you share the pulling load with your buddies, and end up with less drag than a scuba tank in this scenario.
Run time is 3 hours--more than enough time. I do not believe any hookah divers on this coast of florida would ever even consider a surface monitor...the very cautious of the hooka set ( like the man who wears botha belt and suspenders, just in case
use the Brownie Egressor system, which has a small pony bottle which fits in your brownie weightbelt ( which also tows the brownie--you don't tow with your regulator and mouth ) and the regulator of the pony bottle is worn on a bungie around your neck ( DIR style) --should a drunken Yachtie run over your Brownie while you are working hard at 70 feet, struggling with a beligerant lobster..instead of having to do a free ascent while already winded, you have a regulator right under your chin, all ready to breathe...It is a hot set up, though a bit pricey. If you have to use the brownie to 70 or 80 feet though, it could be money well spent. In water less than 35 feet deep, I'd be happy to just free ascend, even if working hard. And then you need a monster speargun attached to the Brownie to blast the drunken yachtie, before he gets out of range