I have used ZMed pads for years with no problems. They were expensive, but I bought them before I knew about FW.
I am mad now, b/c it seems that ZMed discontinued the pads I use; the black ons with the outer coating. Now all they have are the ones that look like FW.. and I will not use then b/c I had one under my '06 female's tub, and part of the wiring came exposed for no reason and SHOCKED me.. this pad was rand new and had air space below it.. it terrifies me to think that this could have started a fire or something.. so now I am scared to try anything new.