Last year I bought the TAP BCE-27 cello pickup to test it out. I have bought three more since. I am very satisfied with it.
I had amplified my harps for some 20 years with piezo pickups which I had installed in the early zero years. Due to their old technology I always had feedback problems on stage, the soundboard of a harp is just too big and receptive for sound waves from outside.
The TAP BCE-27 delivers a good sound across the harp's tonal range (C2 to G6), and I have no more feedback problems.
Obviously, when you place any pickup on the inside of a harp's soundboard it will always boost the nearest notes (with the classical position of a third up the board it is around G3). So you use an equalizer anyway. I use the Boss GE-7 with its (only) seven bands, and the result is wonderful. It's what I always been searching for.
I recommend the TAP BCE-27 cello pickup to friends with similar intruments. Of course there are "better" pick-ups in the world, but in my opinion, the real shortfall on most stages is the speaker system and room acoustics. So I am not going to overspend on pickups for small or medium gig venues.
My only missing star refers to the self-adhesive clip that holds the 6.3'' jack socket. It is a simple plastic clip which makes it a bit fiddlely to get the jack connection in and out.
All in all, for this extremely user-friendly price, the TAP BCE-27 is worth checking out.