Re: residental panel grounding
If the panel is the FIRST disconnect (Neutral Bonded to panel) then this is perfectly fine. Think about it, the neutral bar is bonded to the case which the the ground bar kit is bonded to as well. No code violation here or safety issue here.
As far as saving space on the neutral bar and making a little neater install, I generally will use a ground bar kit.
This may be confusing though to the students if they ever work on a sub-panel or a panel with an outside disconnect.