Lets look at it this way, where are the most common failures?

Taco

Big dent towards axel

Spoke nipple pulls through rim

Spole breaks on nipple end

Spoke breaks at head end


Any way my rule of thumb is the distance between spoke holes on a 559 should be the same as a 622 rim for duribility from the big dents which is how I lose rims, so a 36 spoke 622 is about equal to a 32 559 if memory serves, I need to go out and measure some CR18s I have in the shed,