Alan, my experiences with electronic measurement are much the same as yours. I installed my Bell with two magnets and even when calibrating would have my rides be off by a full revolution. I haven't yet tried with a Protege, but will admit to be a little intimidated by the procedure necessary to make it work with one magnet.
I think I could make the procedure work in a pinch, but am much more comfortable with my old mechanical counter. Plus the reality that the Jones counter works in almost any conditions while at least the Bell does not work well when temperatures are cold. I don't much enjoy measuring in cold weather, but race directors schedule races in April, and municipalities are slow to approve courses, so the bottom line is that we bundle up and measure in March in Chicago.
Duane, if you think a race in Illinois has to have curves, you have obviously not spent much time in much of central Illinois. Try driving US 136 west from Rantoul some time...
And one of the reasons I like working with the metric system is that I pretty much find all fractions to be vulgar.