I am sure that many of the operators of aircraft with the 600 KG MTOW would breath a sigh of relief if the MTOW was increased to just 700 KG its a fine balancing act between PAX weight and fuel on board. Seeing that many of these aircraft are already approved at 700 KG MTOW by the manufacturers. Its a no brainer from a safety point of view. This should also apply to the same aircraft registered VH for all the same reasons.
As for the 1500 KG I leave that to others to comment some of those aircraft captured in this proposal require a bit more knowledge and skill to be safely maintained.