Power Grips for Canon EOS cameras

[Edward]

Does the addition of a power grip increases the number of frames/per second that can be shot with some models of EOS cameras?  Recent EOS camera manuals state the addition of the power grips just increases the number of shots that can be taken.  But if I recall correctly, when I owned the the Canon 40D and 50D the addition of a power grip increased the number of frames per seconds attainable. Am I correct? 

[HDCamTeam]

We also use battery grips when shottig stills, they're geat, improve handling a lot, extend shooting time, etc,

Unfortunately battery grips are not so greal for video, unless in specific conditions or situations, because they add weight (to the already heavy Support system), and decrease stability (specially when using long lenses, stabilizers, dollies, sliders, etc.).

We mostly use the camera without battery grip when shotting video in a production.But when shouting video handheld in some situations the battery grip is just fine.