The benefit is less rotating mass -- remember 1 pound of rotating mass= 7 pounds of stationary mass as far as performance gain goes.
Sheds snow out of the suspension = You carry less weight around in the skid
It makes the track more flexible = less rolling resistance
( a friend has 5 holes across on his cmx like a wet noodle)
I only do two in the middle call me conservative
The best is------All this is free
But they do suck on water.
I have run ported tracks of and on for 4 years now with 0 failure even on turbo sleds , so I would not worry about durability - with the 2 holes anyway But than he has not killed his 5 holer on the cmx in 3 years either.