I tested the current version (which uses 2 canvas objects) on a couple of machines and I do have to make that trade-off... Like, it still works very well on any 2-3 year old desktop machine and it works well on powerful Notebooks (like the Macbook Pro), but if you have an integrated intel gpu, you're literally screwed, means: you'll get between 10-20 fps.
The current version of Sein isn't optimized yet either, I'm pretty sure I'll get more performance from actually optimizing the graphics, shaders that are being used, etc., but I don't really think I'll get to steady 30fps for people with really old machines or really crappy GPUs.
On the other hand, Braid isn't working well on low level machines either and only supports 2 resolutions, so I don't think people care that much. As long as one resolution is an HD standard and the other one is a monitor standard it should be good to go.