Yeah, I don't mind manually advancing film--almost every other camera I own is a manual advance. My issue with the Speed Grip E is that the actual position of the advance with respect to the position of my thumb is awkward, and when I used it I always found myself transferring the weight of the camera to my left hand, releasing my right hand from the grip, sliding my hand up so my thumb could confidently catch the advance, then stroking the advance twice, then sliding my right hand back down the grip, gripping it and transferring the weight of the camera back to my right hand. It was very clunky and cumbersome, but advancing the film without moving my right hand was worse.
Personally I still prefer the WLF and no grip over any grip, but the prism and grip provides some flexibility over the WLF alone.