I carry 2 kg... but that is with a 5kg backplate, Kent Tooling frame and 2 x 1L cylinders - one suit inflate and one O2. I guess total weight would be about 9-10kg. That also allows for two 80's as bail out - one with quite a bit of helium.
In the sea with my standard meg fitted with 2 x 3L fabers, a DUI Cf 200, artics etc I use a 5kg backplate with a 1kg lifting bar and 6kg of lead on my belt. I do carry quite a bit of natural buoyancy( 5 foot 10 and 16 stone)
We are still using the old British measuring system. I am in a neoprean suit. With a six pound backplate and a three pound handle and 19 cubic foot worthington tanks and a six and a half pound plate weight, I need two pounds. The Meg is ass heavy. The plate weight was the best thing I have done as it moves the weight up. I have also gone to lighter fins. I have about twenty five years on the old Jets, and have yet to find a light fin I like as much.
I am five foot eight inches tall and weigh 135 lbs. I have no idea as to how many stone that is or how stoned I am at any given time.