I've been subscribed to his videos for a long time now…That dude is a BEAST. Truly.
As I understand it you guys don't recomend using the OHS to add lots of weight, but generally as a technique exercise to help with the front & back Squat. Am I right in this understanding and if so what are the pro's and con's of prioritising the OHS over the other variations?
Well, OHSQ is just difficult to progress on. Most people hit a ceiling and then they stay at it for a long long time. BigMuscleMilk is also an example of this, actually: his OHSQ is huge but it's been around the same mark for a very long time now. It was in the 185 kgs and now it's 190 kgs. And it's been around this for more than a few years, as far as I remember.
You CAN do OHSQ and focus on it, it will just require you to be patient and it will take time (if it is even possible) for you to hit 190 kgs on it. But yes, with some dedication you CAN hit your ceiling fairly quickly.