It's very well thought out and better than YDS, and since it actually exists and has the backing of an organization might just be a simpler thing to adopt. I'm not sure we really need to subdivide Class 1 but it doesn't hurt and can help disambiguate between it and simple Class 2 (or at least show that a 1.2 might be felt as Class 2.0 by someone depending on experience/skills/height/morale/energy/etc).
My thoughts on it there in response to someone:
Their 2.2 seems similar to my 2.5.
I don't like combining exposure with difficulty - it's one of the original flaws of YDS and it continues here. I've been on terrain that would be 2.0 according to their rating in terms of difficulty but had fatal exposure - is that a 2.2 due to exposure, even if it's a straightforward slab walk? You can try and parse down "risk" as being tied to a fall being less likely on easier terrain, but I think just listing exposure is simpler and fits how people think of terrain better.
Tying routefinding into ratings makes some intuitive sense, and works in most cases, but there are spots that can be more technical but obvious in terms of route finding, or passes where a lot of people end up on Class 4 instead of 2 due to a poor choice 2/3 of the way down.
Overall it's better than existing YDS and a bit more straightforward over my system of combining suffixes ala YDS Class 5. Given that it's going to have a lot more traction it just might be worth using heh.
One thing I like about my system is that it makes it clear when class 2 is less desirable than class 3 - I haven't done sky pilot or king col's but despite them being Class 2 have loose exposed terrain vs say Valor pass which is a bunch of slabs with a super simple fat crack of 3 or two.
Having King Col at 2.2 and Valor 3.0 in their system makes sense in terms of difficulty, but that puts the risk of injury at the same level on both... which isn't true at all! Comparing 2 S X and 3 makes it lot clearer to me at least. It's not usual for me to choose to do some stable 3 over loose 2 when I get the chance. Desirability of terrain isn't linear according to difficulty of movement.
The breakdown into 0.1 and 0.2 systems is very thoughtful, but also feels like it can get into trouble - I don't carry a theodolite with me when I'm backpacking and route finding can change the maximum angle of things. Just stating the general type of movement over terrain (1, 2, 2.5, 3, 4) makes sense combined with standout aspects of terrain (S/C & PG/R/X) to me as people can look at modern maps with slope angle shading and get a feel for the steepness of a pass. It's also less subjective than what people "feel" a section is in terms of simplicity of holds etc.
