Vendo -- Thanks for the kind words! You've got a tough decision, in that from a strict standpoint of being able to receive and select an FM signal, the FM-100-B, FM-200B, and the R200 are all basically identical having (for the most part) identical circuit topology. Therefore, it won't come down to one unit "pulling a station in" any better than any of the others one will. It will really come down to features.
The FM-200B of course has a front panel level control, that will allow that unit to operate without a preamp if necessary. It also has the Microtune feature, which allows the tuner to automatically home in on the center of channel, as well as a coax 72 ohm antenna connection. But these, and the extra front panel indicator lamps (over a 100B) don't allow the 200B to actually "perform" any better than the others reception wise -- although from a technical standpoint, using the 72 ohm coax input on the 200B allows for slightly lower noise performance.
The R200 doesn't have a front panel level control, Microtune, or coax antenna connector, but it does employ a first class AM section, sporting an RF amplifier stage, as well as two IF stages with selectable bandwidths, and a whistle filter. That's the kind of design elements that the very best AM radios had back in the hay-day of AM radio, including the ill fated early AM-FM stereo efforts.
All three units employ the same excellent MPX-sub-chassis, and both the FM-200B and the R200 employ the same identical (and excellent) audio output sections -- which is where the FM-100B falls behind it's more sophisticated brethren.
Where as the FM-200B and the R200 employ separate dual triode stages (12AT7s) for the left and right audio output sections, the FM-100B makes do with a single 12AX7 to serve both channels. It's weakness is that when the rear panel gain controls are well advanced, this tube can be overloaded, where as no such overloading occurs with the designs used in the 200B and R200.
Other than these feature differences then, they're all about a tossup in terms of FM performance capability. If the front panel level control, Microtune, and coax input does it for you, then the 200B is the deal. On the other hand, if you like to listen to AM or do any DXing on AM, then the R200 gets the nod. But don't count the FM-100B as down or out. As long as the level controls are not advanced over half way, it plays just as nice as its more glamorous cousins. I know you weren't asking about a 100B, but I'm just trying to show that its right there in the hunt as well: just because its a stripped down model, doesn't mean it can't play every bit as good as the big boys where it counts. As a said, you've got a tough choice!
Dave
