On the 14.5M Klax recording:(posted 8776 days ago)This is definitely doable. The most likely route is to clear 1-5, then warp using the 4 drop/100K every time you make it to a warp, and DO NOT use the secret warps.
As for the difficulty ramping... I imagine that if you had enough caffeine in your system, it wouldn't be a problem to keep up (unless it can get ramped up to the point where it's doing the conveyor filled all the way across with tiles on a row, which I doubt). It would, however, take work.
The best stage to start racking points up on would be Wave 3 - since it requires diagonals, you could theoretically make "sandwiches" repeatedly. However, it's the first stage to have seven colors (Wave 1 has four [red, yellow, green, orange], and Wave 2 adds blue; Wave 3 adds purple and white), so your odds on getting the colors to come your way are not good.
Still, I think it's doable.
I'm wondering what the record on the 2nd prototype set of Klax is, though, or if there is one. One million should be doable without much trouble.