I've gotten mixed results.. I've got the 4.5 qt model with the screw-type base. Speaking only of mixing the meat (not grinding) I haven't found that it was too stiff for the motor, however, for some reason it just doesn't seem to do quite as good a job as hand-mixing. The other concern, similar to bread, is that the mixture can be over-mixed so you have to stop the machine somewhat regularly, test the mix to see if it's where you want and then go longer as needed.
With the smaller sized batches you're doing I think it's worth the experiment. Besides, if you overmix a batch you can always just toss it into spaghetti sauce! (the meat, not the KA
)