Anybody with experience with online double integration of acceleration?
Any filter within your chain can remove useful information. The kalman filter way is applicable when you have/use a good model of the error, and you have some auxiliary sensor (like GPS, or images) to confront to the result of the double integration (DI). I dont know how good your acc is, but a military one, for example, can drift so few after the DI, that it doesnt need any auxiliary sensor. However, you cannot expect the same result using this cell-phone acc, though. The limit of goodness is defined by your application and the type of sensor you have.