I have the Bird PEP kit, it works fine. You lose nothing at all on CW for key-down carrier measurement, but in the PEP mode each "dit" is indicated as the full key-down power. You can also switch between PEP and ordinary (rms) readings. The only drawback to the PEP kit is that it is battery powered, takes two 9v batteries to run it and the batteries drain pretty quickly if you leave the unit "on."