typing biometric software has been around for a long time (biorhythm) and from what I remember from years ago had issues with users typing in from different devices all the time, laptop to ext keyboard, iphone to ipad with keyboard, kiosk, etc... I don't think it would be more secure or as you put it "much more secure" than say, user/pass and a push notification as the push notification is out of band. These used to be called 1.5 factor as it wasn't quite 2 factor.