Are Jet-tone & Parduba mouthpieces good?
A Parduba is a bad choice (as is a Jet-tone) for players who allow their lips to extend into the cup as they play. Those mpcs with little or no cup will stop the buzz as you bottom out.
As for the Parduba Harry James played the HJ or shallow models. He had a pretty nice sound too. We should all do so well.
I always liked the basic design but not the rim. There are a number of copies of this idea that are not as good. The Callet cv (the second cup is only 1/4 as wide and not as deep).
Jet-tones use a similar idea but there is a curve instead of a shoulder ridge going from the first to the second cup. And JT second cups are not as deep as Pardubas.
Schilke made a few mpcs with a widened second cup this is a very small second cup indeed. Schilke even cut several mpcs that were like the Callet cv 10 years before Jerry did. I have one.
FWIW I LOVE Jet-Tones.