Back to the original quesiton of risers for a 14 year old... Here's my experience...
I started with the Cutting board riser plates under snowpro bindings two years ago. it's a good feel, but only for powerful riders. the leverage created makes the board very unforgiving once on edge. risers also decrease edge change quickness... cutting board risers raise the rider an additional 10mm or so, and take about 7 to 10 days on snow and in gates to really get the feel for...
now i ride the Spirig Hangl Plates and i would NOT recomend them to anyone under 150-160 pounds, simply because they make the board SO HEAVY. Heavy can be a good thing, as my board slices through crud, bumps, etc.. but it also weighs in at 20.02 pounds. you need to have enough strength to "muscle" the board from edge to edge. once it gets going though, it is hard to stop. in GS i am not so concerned about edge change speed, as i would rather have the dampening and the leverage that the hangl plate offers.
on a side not- i have not set up any of the 9 kids on my snowboard team with risers or hangl plate systems.... i did give my cutting board risers to a 19 year old graduate of my program and he loves them. he's becoming a more acomplished rider, and had been training for about 6 years..
as phil fell stated earlier, at 14- there are so many more things that are important ot snowboarding and technique other than this avenue..
-and the schooch brothers may still be riding the hangl plate system for GS , I have only seen this on their slalom sticks...