I doubt the blade flexes by more than a mm or two, thought I don't know.
That's all that's needed. If it flexed by a quarter of an inch, then it would be impossible to jump safely in them. The blades only need to flex a little to disperse energy and prevent it from traveling up through the boot to your foot and up through your body. The Revolution blades achieve that better than practically anything else you can do to a skate, and with virtually no drawbacks except price and a clicking sound you may here when landing jumps.
So sand the outsole a similar amount to make it thinner, and you will compensate for the height-above-the-ice issue.
You're equating the height of the boot off the ice to the space between the actual sole of the boot and your foot. The two aren't equateable. Both provide similar benefits, but can be done in isolation of each other depending on what the skater needs. Maybe I would have kept the stanchion height out of it since it just kinda of diluted my point.
Sanding the outsole is not going to eliminate the effect of your foot being further off the boot when using a thicker insole, nor will it give you back the control you can lose from putting your foot further off the sole in the boot. Yes, it can increase control a little by putting your foot closer to the ice, but that's in isolation of the main issue I was addressing in my post.
On the other hand, a lot of skaters prefer to be higher over the ice. It's one of the many parameters of difference between various blades, and there doesn't seem to be any real consensus on which blades are best. So if I wanted cushioning, I would add a mm or two of squishy material, then sand if I wanted to be lower over the ice.
And in a couple weeks you'd be replacing it because the cushioning was gone since the material got compressed so much, assuming you're jumping regularly. And before you noticed it, you'd probably have sore heels or other issues in the skates (heels start slipping because of the extra room, etc.).
You cannot sand off enough of the outsole safely to account for the difference between a P99 and a Gold Seal, or an Edea Boot and an SP-Teri.
The amount you'd be sanding off would be negligible compared to the difference between these blades and/or boots.
Incidentally, flexible blades and compressible soles or shims aren't the only way to make landings softer. Virtually any land dance teacher, and many skating coaches, can show you ways to absorb landing impact smoothly into your body, instead of landing too "hard". If you are worried you might be fracturing your bones at your current skating level, it might be worth talking to your coach about this.
No, there is lots of choice.
The issue isn't really the lack of choice, it's price.
Figure Skaters don't often get to test drive equipment like the newest Toyota Camry.
Some OEMs have a money back guarantee, but do you want to drill extra holes in your boots so you can test out some new blades, or risk throwing away $600+ because you mounted blades on some boots that you ended up not liking even though they were raved about by everyone else at the rink? We often don't get to test drive, so people stick with the status quo because it works well enough for them and their skating isn't necessarily suffering from it (even if they can theoretically benefit from the better tech). I don't blame them. Economically it makes sense.
But really, most fitters will recommend a more appropriate boot brand (stock of custom, whatever is most appropriate) rather than put that much work into a boot, and in some cases it's simply impossible to match the other boots/blades given the solutions you've listed (some of which require monitoring as they aren't permanent). They are useful in a pinch, especially if you cannot yet justify replacing the equipment, though, so still useful to know!
I had pennies and nickles glued to the outside of my Super Feet in my boot to level my foot off at one time, so I'm not foreign to "do-it-yourself" when you have to do something to make the skates usable. Added a ton of weight, but it was totally worth it cause I could actually skate without feeling like I was standing on Hot Coals.