Not really, Matt, I can remember talking to both David Harris and an operator of a single-cylinder FR1 genny, both said the same thing, it was marginal at best. Twins and upward had enough power reserves to get over the internal losses.
There's an FR1 on ebay at present.
Peter
As a prior owner of an FR1, I agree. Plus, it was a high-maintenance machine, and awkward to work on. An inspired design, but give me a CS any day......