Jason, that's the best bet. The ranges of resistance-per-foot from one brand to another (or even different series of the same brand) varies so widely that the stock spec is kinda useless. Some manufacturers put the specs on their sites.
I dont check mine when new but check them when an issue arises - if they are all the same or close [resistance per length] and I dont have a fire-fly show at night with misting water, I dont sweat it myself.
Sorry to not have any great answers. Maybe others can be of assistance.
My friend who races a Monte SS stock car has a set of blue MORSO and for some reason I think they are 10mm but they might be 9mm can't remember. I am on his pit crew this year so thats pretty cool I guess