Thanks for those suggestions irondork. I may well mention that the growth rate is actually falling, but even if it remained at the current level....
I agree that many JWs would answer "yes" to the 1 in 500 scenario. I've tried to mitigate that somewhat by mentioning a number of hypothetical scenarios including varying worldwide death tolls. The idea behind this is to get the reader thinking it through properly, which the Society doesn't encourage you to do. A true narcissist will see themselves as that "1 in 500", whereas a balanced/thinking individual would see that the very notion of 499 deaths for every Armageddon survivor is ridiculous - and that's assuming Jehovah saves nearly double the amount of active Jehovah's Witnesses.
Cedars