In reply to Blue Straggler:
Just took a Belkin job on a roadtrip to and from Font. Generally it worked very well, but definitely needed a lot of shifting around on some road stretches to find a clear signal which would have been fairly tricky for a driver without a passenger. That said, the French airwaves seemed really crowded and there was no problem in London.
Antennae position will have a big impact; we could usually get much better signal by holding the transmitter against the radio, presumably getting round the problem.