VENUS is real time data illustrating what you say Ted, about pressure. If you scroll down to Live Data-Strait of Georgia you can see the difference between 350 ,450 and 900 feet. 1 dbar is about 1.5psi.Yes depth (water pressure) plays a big roll in whether a body will float to the surface. As the body decomposes it generates internal gas which is what floats it. The pressure from the water compresses the gas reducing the volume. Let's say that at the surface, decomposition produces 1 gallon of gas which would be about 8 pounds of lifting buoyancy.
At 33' the pressure from water doubles sea level atmospheric pressure, gas volume is half, lift is reduced to 4 pounds.
At 99' surrounding pressure is 4 times the surface, volume is 1/4, lift is about 2 pounds.
At 231' pressure is 8 times the surface, volume is 1/8, lift is about 1 pound, body isn't ever going to float from gas generated by decomposition.
This is reality: Deep water oxygen/scavengers