Testing the Yamamoto HS-4 Carbon Fiber headshell.

I had a very similar experience.  My turntable is a Technics SL1200GAE, headshells compared are the one sold by LP Gear as the Zupreme (which I believe is the Jelco headshell) and the Yamamoto HS-4S carbon fiber.  You have done a much better job than I could of describing the difference in sound in favor of the metal headshell.  At least to my ears, with my arm, and the cartridges that I have experience with (Cadenza Black, Winfeld, Experion).  It is certainly believable, however, that with different arms/cartridges etc. that the results could be reversed.  The lesson to be learned here is that it is not possible to draw universal conclusions about the many variables in our hobby.

@nandric I've been listening to, and participating in, @halcro cartridges comparisons. One of the most valuable outcomes of that wonderful thread is that we all pretty much agree on the results. If that is true, then, why are we hearing such differences with these components?

Thank you @billstevenson

I've been wanted to try the HS-4, and I'm glad I found this thread.  I'm currently using a Yamamota  HS-2HS-2 (Asada Cherry Wood) on my Technics 1200GR - Dynavector DV20xL.

I like the HS-2HS very much, and the other headshell that's in my rotation is an Ortofon LH-9000.  The Ortofon, used with the same cart, pulls more detail, but not quite as smooth sounding as the Yamamoto.

Hoping to find something that's in between the two.

Dear Noromance, By no means am I implying that you or your judgement are "wrong" or that I am "right". Your Garrard set-up is very analogous to my own modified Lenco set-up (idler-drive, slate plinth, massive after-market bearing). On the Lenco, I use a DV505 tonearm and on that tonearm I most often mount MM or MI cartridges. Those types do not put so much energy back into the headshell/arm wand, because of higher compliance. The Lenco also runs with a Boston Audio platter mat. (Your worst nightmare, apparently.) This set-up feeds the MM inputs of a Manley Steelhead, modified a bit, and the Manley drives the built-in direct-drive amplifiers of my Beveridge speakers plus an outboard woofer separately driven by a Threshold amplifier. I’ve also used the CF headshell on my Victor TT101 with SAECSS300 platter mat and a FR64S/B60 tonearm, also feeding usually the MC inputs of the Steelhead. It was Halcro who originally suggested to me the possible merits of the Yamamoto, and I am happy that he did. But I wouldn’t say the Yam "blows away" all other headshells; I would say that it is "good", at least a little better than the various metal headshells I have used on these systems and affords a certain solidity to the music, for want of a better word. I do think that the headshell needs to work well with the cartridge. Cartridges on the Lenco have included the Acutex LPM320, B&O MMC1, and Astatic MF2500, but also the MC type Audio Technica ART7. On the FR64S, it only recently got a second Yam headshell and right now I have the Dynavector 17D3 on that one. I think the 17D3 is the only cartridge I’ve used on the FR64S since installing the Yam headshell, but I also have run the AT ART7 and the Acutex on that tonearm. The FR64S has an inherently high enough effective mass that you can get away with a light-ish headshell, like the Yam and still be in the right range for resonant frequency with low compliance MCs. (But surprisingly, it sounded great also with the high compliance Acutex.) Like Chakster, I cannot hear much difference between the BA mats and the SAECSS300, except that both are better than anything else I’ve tried by a fair amount. Or to put it another way, there is a qualitative difference between these mats, but I like both. I don’t think or expect that one headshell would be best for all occasions; I use an Ortofon LH9000 (18g) on my Kenwood L07D with Koetsu Urushi, because I think the Urushi really sounds best with high effective mass, and the OEM L07D headshell is only about 10g. I hear a big improvement with the Ortofon. Oh yes, and the L07D sports a custom-made pure copper platter mat.
Could it be that you are liking a certain resonance in your system that the BA mat and/or the CF headshell is taking away or dulling? It could equally be that my own systems generate a certain resonance that needs squashing. Such is life.