I think that whole construction with ultralight, microlight, LSA, sports equipment is among the worst bull**** ever happened to aviation and its progress.
All these machines fly and the sub-weight categories were only born to bypass the stupidity of certification and regulation authorities, so isn't it time to get rid of all that fight? There is no use in discussing 600kg or 750kg or 813.254kg - there is no physical reason for that distinction.
Many of us warned that the authorities would regulate private aviation to extinction. They also warned, after the sports utility workaround was in place, that technological advances will come from the ultralight/microlight and experimental sector quite soon. It did.
Why can't we go simple? There is an aircraft and it has different MTOW/MTOM. One set of regulations will increase the burden on the current ultralight/microlight/LSA community, but lighten it on the more classic GA side.