Hank49:What if you only need 4 lbs of weight and a plate weighs 6 lbs? And is streamlining really that big of a factor? When I'm diving I'm hardly moving at a pace where streamling is needed. It's like a little flick and on to the next spot to look for this or that in the reef. (I'm not arguing against BPs at all. Im trying to evaluate if it's worth me getting one so thanks for all inputs here)
Here's how I got into a BP/W. When I was learning I was in a rental stab jacket. The "cummerbund" was KILLING me. I had 28# of lead on my belt. Not necessarily WAY overweighted (although I was to offset newbie anxious breathing) but my trim was a train wreck. Think of a balance scale, 28# on one side (my waist) and buoyant lungs and bubble wrap (air all around you BC) on the other side. I weigh in a 230# so I need a bit more weight than a 100# diver. I was trying to figure out all this stuff while learning to dive. I stumbled on SB and met FredT. He just happens to make backplates etc. and the rest is history. I bought his gear, setup a rig and immediatley got the weight where I needed it. So I never really got to work on trimming out a decent Jacket BC to be fair. You may be diving that BC fine but may not know if you're "missing" anything without trying a BP/W to compare. Maybe you can borrow one from someone. If a 6# plate is too much you can buy an Aluminum one. There are many options for weighting depending on the plate you get. Mine uses STA's (single tank adapters) that are 2# each. So my 9# SS plate gives me 13# on my back and my 2# Aluminum plate gives me about 6# total. When I dive wrecks in North Carolina I use my AL plate, steel tank and 4# on my belt. The 9# plate was just too heavy with a steel tank in a 3mm shortie so I got the AL plate. But when I dive an Aluminum tank in my 3mm then the 9# plate and 3# on my belt is perfect.