When the head on my Concord antenna was damaged, I too found that replacements were not available. I removed the head and replaced it with the Jack antenna. I had to make my own mounting bracket to fit the 3 legs of the Concord. I made my bracket from multiple pieces of 3/4" X 3/4" aluminum angle. I had to put a stop on the bracket to keep the arms from going "over center" when put in the travel position or the antenna would not raise.
I really can't compare that much but I do believe that I get better DTV signals with Jack than I did with the Concord.