@smoffat, I tried a Quintet Mono and an AT33MONO on my VPI Classic 3, using arms that were best matched to either cartridge. The AT33MONO is relatively light and of low compliance so it matched best with my SS black damped Classic arm; the Ortofon was matched to my aluminum Classic arm. I preferred (prefer - I chose it as my mono cart) the Ortofon. It is more neutral than the AT33 without meaning it sounds dull or lifeless; it rather has much less in the way of "tells" in how it reproduces the music. The AT is also a bit softer in the extreme low end, and a bit (only a bit) splashier in the cymbal range. The AT does, arguably, do a slightly better job in reproducing the upper bass and lower midrange.
All of those observations are small compared to what drove my decision. The big takeaway for me was that the Quintet Mono pulled me into the music much more, and actually got me into forgetting I was listening to my TT and sing along to what was playing. For a guy who goes out of his way not to sing I figured that was a pretty good sign. The Ortofon made it seem more real to me.