Hi All,
Stephen's point is a good one.
Major thoracic bouyancy reserves are a bugger when using a continuous harnes in the usual hogarthian configuration. Crossing the straps over the shoulder is a good work-around for the narrow torso, but isn't much help for the plentifully fleshy. Those with rather a pear shaped torso, especially if it's female, usually find the D rings leaving bruises on the armpit area. Harnesses with some type of chest strap can usually mitigate that considerably.
Another item that's not been mentioned yet, but shouldn't be overlooked; is that a BP/W with a properly adjusted harness takes a fair amount of flexibility to don and dof, especially on a boat. You don't have to be a contortionist, but many of the plentifully fleshy are limited in this respect. For overall ease of use with most of the plusses of the BP/W and harness, I'd suggest a good look at the DR Transpac or something similar. The Tpac has a lot of adjustability for sizing as far as waist, and torso/shoulder lengths. It's a piece of cake to don and dof and while I like my BP's better, I managed at least a hundred dives or more with doubles in the Tpac, all very comfortably. Add a Venture (or any O wing), and it's a sweet singles bit of kit.
Always try before you buy, if it's at all possible.
Darlene