HRC parts are not the final word. As with most commercially available stuff they are a good starting point and should be played with. On my old race bike I epoxied the plastic stuffers into the valve and then filled in with more epoxy and got grinding.

15 or so years ago I spent many hours on the dyno testing reed valves. This was after reading through lots of Yamaha white papers on the subject. Very interesting and worth searching for if you can be bothered. There's a lot about carb to reed area ratio and what they say makes sense, and tests out as gospel on the dyno and in the real world.

Remember the old steel reeds? They always seemed to fail at the most inconvenient times. This was basically down to fatigue and constantly hitting their natural frequency of resonance, which would cause them to slowly but sure destroy themselves. Thankfully, fibre and carbon reeds have a high frequency of resonance that you dont get to, so they don't (usually) fly to pieces. Where they do suffer is from the constant heat cycling and fuel washing, which breaks down and softens the epoxy holding them together.

If you want to play with reeds then you should really be looking to widen them first before increasing the lift. If you can get the same area but with less lift them the petals react faster and performance is improved. Remember that at 12,000rpm that poor little petal is opening and slamming shut at 200 times a second, so if it only has to lift say 10mm instead of 11mm then that's 2mm less travel per cycle, or 40cm per second. That's gotta be a good thing when you're looking for fast reaction times.

Another thing about lift is that if you try going too high then there's a chance that the reeds won't hit the stopper and they become unstable. HRC and others have got round this with stiff reeds or extra supporting reeds and don't actually use a stopper. The reed tension is sufficient to control this.

Anyway. It's bedtime.