the lack of boundaries will make me continue to use your app! it is how i ever felt those apps should work in the first place. you nailed it.
only critic i have now: the fake width of the traces are ok for testing out the app. do a few swipes and something similar to a brush drawing appears. nice. but using speed for that is completely unintuitive and impossible to "use".. no way to make a thin straight line (have to do it slow, so it ends up jittered) and no way to do a short bold line (no way to get to speed). either find a way to get finger pressure or just leave it flat.
and a feature request: add simple text tool so my schema designs are easier to do :)