I think it may depend on how you don your gear. If you have a pedestal to prop up the tank to back/shoulder level, then the traditional one piece webbing will probably work nicely. I primarily beach dive and do not have a stand to raise the tank to shoulder/back level. I have to kneel down, slide my arm through the left shoulder strap and then through the right. Having some slack in the shoulder harness, makes this easier for me. Likewise during the doffing process, being able to add slack to the shoulder straps lets me easily remove the BPW, as I lower it on the ground.
Also, the shoulder straps of the Transplate anchor to the waist band and not the back plate. I honestly don't know if this is advantageous or disadvantageous.