@Degen I did not miss the ratings of a 17 series torch, I know they are rated for 150, I own 4 of them and use/have used them all well above 150, and yes they get hot, are you going to burn one up on a 200a machine....very unlikely, that thing is going to duty out long before you kill the torch
I said a 200a because that's the class it's lumped in with, 20a this way or that does not make much difference, it's more marketing than anything else, just like having a 250hp V6 is not practically much different than a 265hp v6
The 100% duty cycle for welding is misleading, it does not really matter as no human can weld at 100% duty cycle in the real world...the time to get a new rod, repositioning yourself or the part, the time between each weld, taking a swing of your coffee, pee breaks, etc etc, it all adds up, 60% is the commonly accepted number that actually matters, that is where you can realistically weld steady
So what I'm getting at with that last bit is, forget about the 100% rating
Honestly you're putting to much stock in the tungsten selection, they all do the same job, the only real difference is how long they last and how well they handle contamination.
I have taught many people how to Tig weld, tungsten selection is probabaly the least important thing, if you have the hand skills to Tig weld it doesn't matter Wich tungsten you have in the collet so long as it is sharp