I recently tried the Black Widow and Green Dream PHTs on my cartridge, which is a My Sonic Lab Signature Platinum, connected to a Manley Steelhead preamp.
I tried each version for a couple of days and concluded that they were not for me.
Yes, they did alter the sound, and differently from each other, but they did not improve the sound for me. In fact, I thought they took away the purity of the sound it produced without them.
Perhaps they work better on lower end carts? Perhaps some of the other versions would work better for me? Whatever the case, I sent them back for a refund.