Fidelity Research cartridges

Any FR cartridge experts out there? Raul? Dertonarm? Syntax?
I have had an FR-7 which I bought a while ago. I tried it ever so briefly when I got it on an arm I now recognize as not being able to handle that weight (close, but no cigar). I just now pulled it out for kicks and after getting it adjusted with the big counterweight, I am VERY pleasantly surprised. Actually, I'm feeling kind of bubbly. It does not dig out the utmost in detail, but it just sounds very right.

Are there any other FR carts out there which are real steals if still in good condition? I know the MC-702 and the FR-1Mk2 and Mk3f by name, with good reps being assigned to the Mk3 and the MC-702. Given that the MC-702 and the FR-7 look quite similar, and they were offered at about the same time, what is different? And is the FR-7 just an integrated headshell version of the FR-1Mk3?
S4 headshell with which FR 4S was sold weights 14,5 g (or it was supplied with 19 g headshell???)
So if roughly  to evaluate FR-64S + 7f :
35-14,5+30=50,5 eff mass, g
So if to go further and to compute desired  resfreq [Hz] 9 - we are getting if to use 11 cu --> 28,4 g  tonearm (Total)Effective Mass needed[gr] ; or roughly 35 grams tonearm eff mass needed in case of 8  desired  resfreq [Hz]

It seems that there are owners here in Audiogon of 64S + 7f or 7fz --> have you tested with test record lateral resonance frequency in your system? Could you please post here results?

Anything between 8 - 15 Hz is ok, it is not necessary to have 8Hz resonance freq, more like 10-12Hz in theory.  

The FR-64s and 64FX are two flagship models designed by Ikeda-San, both are perfect match for his flagship cartridges such as FR-7f and FR-7fz. The only difference is the optional W-250 counterweight for 64fx arm which is a must have for use with FR-7 series of cartridges. 

There are long versions of both arms made. 

I am using FR-7fz on my 64fx with W-250 counterweight and N-60 nut.
and i have not mounted yet my FR-64s with B-60 base and with IKEDA 9 III cartridge. 

However, my current favorite is Miyabi cartridge by Takeda-San on Lustre GST-801 tonearm. 
Dear chakster (only teasing) By FR-64 S there is an extra weight but
lighter than standard; 170 g versus 250 g. I see that by FR-fx the
case is the other way round. Probably to compensate for aluminum 
construction(grin).  If I am well informed Takeda-san made 3 carts the
best among them is called ''Miyabi Standard''. 
 If I am well informed Takeda-san made 3 carts the
best among them is called ''Miyabi Standard''.

I have it too, but did not tried yet as my Miyabi MCA is a stunning performer. 

Dear chakster, Are you some kind of masochist?  How can you
resist to try out your Miyabi standard AND Ikeda 9. III?