The ideal weight of a diabolo may depend on the diabolo style and the environement.
My experience with numbers practice :
I have been training for years with a 270g circus Henry's diabolo. Then I switched to the Sundia EVO with 235g and that made everything run easier for numbers. Meeting Haavard in Norway, I was inspired to try lighter EVO diabolos. Sundia produced a light weight Evo model. My first impression was that the diabolo is too light. Once I got used to it, my body was able to tune in to more sensitive feedbacks. As a result, I think that improved my accuracy. Not to mention a huge gain in energy saving.
In the last 2 years, I have been using 200g EVO diabolos and I can't switch back to heavier ones.
My experience with one diabolo :
I have settled with 235g diabolos which I find good enough for the stage. I think I could go up to 245g as I am enjoying a strong feedback specifically with one diabolo. How much do you think a diabolo should weight?