A hundred feet with a glow motor is fine, but I fly my gassers a lot farther away than 100'. Once or twice I even forgot to extend the antenna.

BTW, I fly JR and as a rule I quit with a range check when it looks like I'm going to have to take a break on the walk back because I'm so far away from the plane. I know of many Futaba, JR, and Hitec radio installations that provide an equally long range check, engine running or not. I don't currently know anyone who flys an Airtronics, so I can't say anything about those.

Those that take the time to listen to and heed the directions of the ignition manufacturers usually keep their planes a lot longer than those that don't. But if you really believe that you know more about a product than the guy that manufactures and designs it.......... Like TKG stated, "you can lead a horse to water."