The Crown Sound Grabber II works great for piano!
I recently purchased two of these mics. I was trying to find a relatively inexpensive solution to the age old problem of trying to mic a grand piano without all the baggage that goes along with that. This situation was also a live concert recording.
I placed two mics inside the grand piano to the right on the harp. I placed them over a piece of sound treatment (for vibration) and angled them at 45 degree angels from one another. I can honestly say this: THEY SOUND AMAZING! (especially considering the investment) I would recommend them to anyone who needs a piano mic solution. They sound better than mics 5X's the price or more. They sounded great live and they recorded beautifully. They get 4 stars only because the construction leaves a little to be desired. They are completely made out of plastic. However, don't let that be a deterrent. Take the plunge. It's a gemstone. You will be happy!
Lastly, my experience at Sweetwater is always a pleasure. Thanks again Bart Good!