I districute Powerisers and Pro-Jumps in the South East of UK, so I would say that you probably have the right model for your weight! Both Poweriser and Pro-Jump will advise you to go to up to the next weight level, especially if your weight fluctuates. My weight is around 82-84kg and although the M80's would have been fine, I find that the M90's are far better for running, jumping and ridiculous stunts.
Hope this is some help.
Pepperkayn