My concern with this approach is not that it makes it harder for purple trades / non-army types, but that it lowers the standard for some of the other trades.* That's cool that the infantry has its own PLQ, but IMO the entire combat arms needs that little bit "extra." Applying this model, if the CAF runs a PLQ and then each trade runs its own "add-on" piece that is trade specific, that may fit the bill, or at least in groups (aka combat arms, combat support trades, service support trades). But if they are going to run PLQ CAF-wide but only the Inf gets its own PLQ mod... many other trades suffer in the CAFs attempt to cater to such a huge width of skill sets.
*I was the Crse O for a PLQ-L at Leadership Company a little over a year ago. The swing NCO I had was armoured and was excellent, and had been there for 3 years I believe. I made a remark that the depth of experience between candidates (one was a PRes musician who had never been in the field before this course, while some were seasoned combat arms Corporals) was making it impossible to apply one standard fairly. Either a bunch of people that don't need these skills fail, or a bunch of people that need these skills and don't have them pass. He agreed and said "that's why I've seen the standard drop for the combat arms ever since they moved to this system. It's fine for the Infantry, they have their own PLQ to deal with the problem. What about armoured, arty, sappers? They are lumped in with musicians."