I see many ongoing discussions on the net that handle about the subcategories in contests.
In my opinion - of course I've also an opinion on this item -, keep it as simple as possible and make a difference in human behaviour in stead of splitting up technical situations.
There is a big difference between single operator and multi operator. Especially after several hours of contesting, a replacement by another operator is a big advantage.
So keep it simple : SO, M/S, M2 (needed ?), MM.
Although this simplicity the IARU contest doesn't comply with this; no they find that an assisted single operator equals a multi-single station. Uhhh ??? I've not enough brains to find the logic on it...
On the technical categories, I agree with QRP (10W), low power (why not <200W with all the new transceivers giving 200W output) and high power - no, correction, better said : higher power.
And here the discussion starts with the question what is the limit high power : 1KW, 1.5KW, 5KW, 10KW ? Does it make sense to categorize high power ? I see many US stations crying that the limit is 1,5KW.
Of course, the FCC doesn't allow higher power. If FCC agrees with 2KW, are we going to change the opinion and go to 2KW ? And what with countries that are limited to 500W ?
I see many of these guys thinking : the high power limit is what I can handle in my station/country. And as many big contests are controlled by US hams, this means 1500 W.
On the other side, the same guys are promoting stacked yagis and multi-tower setups.
Not that difficult if you have 100 acres in the middle of nowhere. Where I live, I can place many towers and stacked yagis too, but my neighbours wouldn't appreciate it, so no possibility.
Keep it simple : 10W, 200W and an open category.
Open category : no power restrictions, no antenna restrictions, SO2R allowed, assistance allowed. But : one operator and only one signal in the air.
Big respect for the teams that can handle 10KW in an M/M environment, foresee enough electricity, avoid antenna and coax burnings in the complete chain, and live in peace with the neighbours when it comes to EMI problems...