I'll just keep the ARMA stuff to myself from now on because I fear it will always leads down one path.
I'm in no way good with a sword (I'm an armor-side addict) but I have met John Clements in person and taken a couple hours of class with him. I'm happy to discuss ARMA in general, though my thoughts have been posted before, I'll give it another brief rundown.
He's enthusiastic. He's had access to period manuscripts in person. He's been "eating, sleeping, breathing" this for decades. He's been on TV. He's been to other countries to present/teach. He's a great teacher, and a friendly guy in person. His enthusiasm really is contagious, almost like Mike Loades. For that, I like him.
He's got his own interpretation of things, and often claims it's the only right one. He's got a "closed door" mentality, and isn't nearly as forthcoming in sharing info with the rest of the WMA community (although he has changed a bit by posting some of the videos, as originally posted here). He does seem to have somewhat of an "ARMA vs WMA/HEMA" outlook. For that, I don't like him.
I am all for multiple interpretations of techniques in manuscripts. There is no "one true way" in WMA. There were multiple masters, and some techniques overlap, and some differ. Looking back at some of the things published 20 or even 10 years ago, even Christian Tobler has put out updated versions of his original interpretations. WMA is a "growing" art, we don't know exactly what they meant 500 years ago, and it's highly likely we never truly will. We can translate and try to decode manuscripts until we turn purple, but the best we'll ever do is put forth our best guesses at what the masters were trying to convey.
Technique drilling is great in a vacuum, as mentioned. The root of it is that unless you have two masters from the same school, who will react with the most likely counters to a specific technique, the battle is up in the air; people new to WMA can be the most dangerous because their actions are unpredictable and their "technique" is often crude - yet it's those exact aspects that could spell defeat quickly if the master is over-confident.
When the krump works like that, it's a great technique, but it leaves a lot to chance, especially with a live blade right next to you. While John's interpretation on the krumphau seems workable, I'd personally opt for striking as far out of range as possible, or closing quickly and taking to the myriad of sword strike ringen counters to immobilize the opponent as quickly as possible.
Again, I'm about as noob as noob gets with the sword, so if I sound completely off-base ... I probably am.