Jason...I was considering your exact combo before, although I demoed the Classic 1 with a DV 20X2 because that's what the dealer had on hand at the time, before going with my current combo. The dealer said the 17D3 is somewhat different from the 20X2 in that it is more resolving, faster, more incisive, and more neutral than the the 20X2 which tends to be a little bit tipped down in tonal balance. There's no midrangey warmth with the 17D3 if that's the sound you're looking for. Just a fast, resolving and neutral cartridge that performs well above its price point. My guess is that the Clearaudio and Simaudio phonos you have owned will be a bit too much of a good thing with the 17D3 from what I have read of their sound. You may want to consider something like a Manley Chinook or a Zesto Andros (if you can go up another few $K), which is still very resolving but will allow some flexibility in contouring the SQ to your taste by tube rolling.
Hope that helps somewhat.