I would think the variance between text entry methods could cause a problem with this for users going between different machines. Typing on a desktop keyboard,

I would think the variance between text entry methods could cause a problem with this for users going between different machines. Typing on a desktop keyboard, versus typing on a netbook keyboard, versus typing on an iPhone keyboard are far from the same experience. Even typing on a short-travel dome switch keyboard versus a scissor switch or buckling spring keyboard could probably change cadence for a lot of people. That said, if a user's cadence "scales" at all (at least for home-row applications, probably not for thumb keyboards) it shouldn't be hard to find the patterns there.