So this kind of thing comes up every year when there's high water: "Will my buddy that's a newbie be OK on the Upper C at high water?" Everyone that's an experienced rafter or kayaker says, "yeah, no problem, it's just the Upper C." To which I say, yeah, it's just the Upper C, but it's at high water. Here's an anaology: Imagine your novice buddy is a 15-yr old kid with a learner's permit who's halfway through driver's ed and has been out on the local streets and taken mom to the grocery store. Would you want to put him in heavy 75 mph freeway traffic? Maybe throw in some motorcycles buzzing past between the lanes like in CA and some really aggressive drivers changing lanes all around him for good measure.
And Yarmony turns into a boat eating hole at high water.
It's gonna be fast, powerful, and a cold, demanding swim if your buddy doesn't make the move right.
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse