Audio Craft AC-4400 and related AC tonearms

The AC3300 & AC4400 were in production for quite a long time. Here's a review of Platine Verdier from 2001 and it came with an AC4400, which looks to have been one of the recommend tonearms to go with the Verdier:
http://hifishack.com/jcv_platine_review.php

I'm very interested in the FR66s & FR66fx, but they are out of my budget... The difference, I believe, is the same as between FR64s & FR64fx: the former is stainless steel and the latter is aluminium. The anti-skating mechanisms are also different.

Some notes, possibly obvious:
- AC3300 & AC4400 are later, more advanced models that command much higher prices (~3-5x) on the used market. I think they were manufactured until the early 2000s. 
- AC3000 & AC4000 are unipivots and AC3300 & AC4400 are "double point support", but I haven't seen one in detail, so I'm not sure what exactly that means.
- AC3300 & AC4400 have VTA on the fly, I believe, but the other features are similar. They all have adjustable silicon oil damping.

[Purely subjective assessment made with a limited number of cartridges and not in a fully controlled or blinded setting:] I have AC3000 & AC4000 and quite like them. They have an open, easy, refined sound compared for instance to FR64s which has a solid, full-bodied sound. I like having both and use AC4000 for chamber & choral music and FR64s for orchestral & jazz.

@chakster I think you read too much into the color match. The headshells that came with FR66s & FR64s were also black. 

The fx-models are later than the s-models, I think. The difference isn’t just the weight, but also the material. Steel & aluminium resonate differently and the surface treatment might make a difference too. The FR-7 cartridges are so heavy in themselves that the arm mass makes less of a difference. For the cartridges, the f at the end means silver coil and some of the tonearms, both fx- and s-models had silver wiring though I’m not sure how to tell which ones.

I think both the fx- & s-would be great with FR-7, though there seems to be a general preference for the s-models. I have both the FR64fx & FR64s, but don’t have FR-7 cartridges. I have used both with SPUs and some other cartridges quite happily. Currently, I have FR-1 Mk3f in the FR64s and Audiocraft AC05M in the FR64fx. Both sound great.

I have used both MM & MC cartridges in the Audiocraft tonearms. I’ve been particularly happy with MC, specifically Accuphase AC1 & AC3, Audiocraft AC03, and Shelter models.

I have the W250 for FR64fx, which I think was needed for SPUs as the default weight was too light. The default weight for FR64s is very heavy, but I have a lighter one for it. 

You could also use a heavier headshell for the other cartridges. I don't know what the part number for the lighter one is. My FR64fx came with it and I bought the heavier W250 separately.