I used 11 kg when I dove drysuit in Japan with 10L steel tanks. Looking at aluminum backplate right now.How much weight are you using now? What type of tanks do you plan to use? What type of backplate do you plan to buy (steel, aluminum, or carbon fiber)?
You might not need to buy an integrated weight system at all.
I would like something versatile enough to cover all scenarios so I'm willing to shell out the extra cash to buy once.