I have never used the Earthworks, though I know they're good mics; personally I recorded several times with a pair of the standard AKG 414 B-ULS, right over the hammers, on the treble side, and on the bass strings, about 2'over them; Neumann KM 184 are real good and bright; my favourite approach (when available) is to use a stereo pair (XY or ORTF)about 7' outside of the curve, then place two AKG boundary mics (but I belive other Boundary mics could be good too), with little rubber suspensions, directly inside the piano, laying over the harp, one on the treble side, the other on the beass strings; then you mix the two boundary with the stereo pair to taste for added definition, the sound is killer.
B&K 4011 seem to be one of the most used by some top engineers.
Hope this helps
L.G.