I imagine the issue is brush lag. because it's not a built-in digitizer it down't work as quickly as the surface, there have been a number of tests corroboratin

I imagine the issue is brush lag. because it's not a built-in digitizer it down't work as quickly as the surface, there have been a number of tests corroborating this, Gabe actually alludes to this in his review when he says "There was no brush lag at all and the pressure sensitivity worked perfectly." there is essentially no brush sensitivity with an ipad (though I doubt you really need it in math notes) and from my limited use (of friends ipad+pen setups) you kinda have to force the pen against the screen to ensure it always writes... in a head to head competition the surface would win in note-taking though the ipad might win for the price....