Big t, I have the alum FredT bp which is 1-2 pounds neg and the heavy STA which is about 5 pounds neg... I chose this because most people seem to think that a STA is the more stable choice and it actually doesn't seem to set it away from your body that much at all. I could have gotten the 6 lb SS bp and the light STA, but that would just about put me overweighted for tropical diving (no ditchable weight anyway) and with heavy doubles, I would actually need a lighter (alum) plate to offset all the weight on my back. With what I have I can use the alum bp without the STA with say a pioneer 27 for tropical diving with just a couple pounds on a weight belt or the with heavy STA and no weights. For heavy doubles, I can still use the aluminum bp and not have to worry so much about being overweight and/or not having any ditchable weight. Options are important to me and with FredT's alum bp and heavy STA, I think I've given myself plenty of options. The heavy STA is a one piece unit that does spread its weight down the length of the backplate and undeniably provides a stronger, more stable unit by rigidly connecting the tank to the STA and bp. The design of the STA conforms to the tank and provides a rock solid mount. The STA is 1/4 thick... so at the most, its sets the tank back 1/2" which I really doubt more than makes up for the added physical stability a STA adds.
Also, I paid $130 for the FredT aluminum bp and the STA. Thats a great price considering I have several advantages (IMO) over having a single 6 or 9lb SS bp. I can travel with it, easily use singles or doubles with the same bp. I don't think the 9lb bp has any real specific application for me personally due to my size and weight needs (don't need much compared to many on the board) and the four pounds the other SS bp would give me over the aluminum is really not enough to worry about. A big reason I went with the bp/wing is to improve my buoyancy characteristics and not being overweight is a big consideration.
