The grip panels on the HK P30 are awesome, but they tear up the skin on my back when I carry in a CCW holster.  I was thinking on belt-sanding one of the extras down so it would be smoother, but it will look like shit!  Are there any aftermarket options out there that fit the P30?  I ended up just buying a USPc to carry, but the P30 would be better in every way, otherwise.

I'm not aware of any aftermarket panels, and you can't interchange the P30 panels with the VP9 panels.  I think you should go ahead with the sanding idea, without the belt sanding part.  I haven't personally done it, but I've seen really nice sanding jobs on Glocks, Pearce Grip extenders, etc, but it took time and patience with gradually higher grit sandpaper until you get to the barely abrasive grit level.  The worse that could happen in this case is that you have to buy replacement P30 panels from HKparts.net, so if you screw up, it's an easily replaceable insert part, not the actual grip itself that's ruined.

If u tuck your under shirt in, the grips won't scratch u. So much more comfortable for any gun.

This.

It also keeps your sweat from creating a patina that makes your couple year old gun look like it's 100 years old.

Take the guilty panel off, and sand it down with some 500-600 grit paper to smoothen it up.

Worst case, you screw it up or hate it, you order another panel for $10 or whatever.

I sanded mine. They look fine. Wipe it with a wet cloth after sanding.