Richard,
You bring up an interesting point about the FR series that anyone contemplating buying one should be aware of. The company that made all the "real" film in the world and packaged it in little yellow boxes decided that they could save millions of feet of film by shortening the leader on each roll. The FR take-up spool winds the film over the top, and combined with the "fingers" used to secure the beginning of the roll makes for an unsecure film advance system with the short film leaders found today. Your have to be sure the film is advancing by watching the rewind knob. It can slip off the take-up spool after two or three frames. Happened to me a lot. I started to burn five frames at the start of a roll, just to make sure the film hadn't slipped off. That, combined with the typical non-working film counter gave one to many surprises.
The FR I is a nice, solid body. The battery lasts forever, or seems to....
The only other quibble I have is with its remote shutter release. It uses a push on bayonet. It comes out rather easily. Not commonly found, either. There's an adapter to use the current screw in style remote release, however it, too is uncommon.
The FX 3 is a great back-up, or travel camera. Lightweight, compact, and reliable. Totally manual, with basically a match needle exposure indicator that uses LED's instead of a meters pointer. It has a mechanical shutter that works in any weather, modern take-up spool that winds underneath, and an old style mechanical remote shutter release found almost anywhere. About the only thing that it doesn't do well is follow rapidly changing lighting, whereas the FR I has aperture priority automatic exposure, a big plus in nightclubs.
Both bodies can bought insanely cheaply on ebay, and a quite a bargain. The FR I was not an inexpensive camera when it was being produced. I paid over a weeks wages (my measure of inflation adjustment) for a kit that included the body, a 50mm 1.7 ML lens and "neverready" case...(great lens BTW)
Pardon the lengthy post,
Joe W