I'm trying to get a handle on what's up with these arms. It seems there isn't alot of info available outside of the most desireable FR-64 and -66 series, though the FR-14s seem to command a bit higher prices.
From what I can find:
The -24, -34, -54 and -64 were contemporaries, with the -34 being shorter, and otherwise progressively more advanced/expensive. The Fr-12 and -14 were later developments (the -12 is shorter, while the -14 has the more common FR spindle-to-pivot/effective length), designed with lower effective mass to accomodate a greater variety of cartridges. That said, I haven't found much on effective mass other than the -64 being pretty massive, with some variants taking it down a little.
A quick search here shows at least a couple who have owned/sold the FR-54, and a few who have owned the FR-64. I'm wondering if anyone has exposure to the other models?
Also, if anyone has experience with an FR64 variant compared to a -54 I'd be interested to get an impression of the differences (at the potential risk of driving up the prices of the relative bargain -54). It seems the -54 was relatively common in Japan, but not officially exported (perhaps) and can be had from Japan for fairly cheap, though HM Customs will provide a suitable rogering to ensure most punters will stick with Rega arms.