i owned tympani 1 bs, my friend had tympany 1ds and has mg3s. i have heard 3.6s and 20.1s .
personally, i prefer the tympany 1ds over all other magnepan speakers. they were listenable for hours without fatigue. the newer magnepans are a bit top heavy.
i have owned the 1.6s for over 1 year. they are ok, but there is too much treble. i use 4 ohm resistors and tubes and there still is too much treble.