Well, for me, its more about bean mass temperature combined with the various milestones that one uses to mark the progression of the roast rather than a specific amount of heat. Youve got to remember that Andy is referring to roasting in a commercial drum roaster and the approach used in other roasting apparatus will require different approaches by the roaster.
Ive found that with a Corretto for example, I reckon I get the best out of the bean by stretching the time to achieving Rolling First Crack(RFC) rather than trying to shorten it. Ive found out the hard way that if I push the roast a bit too hard early on I dont realise evenly roasted beans (through the beans), no matter how gently I take it after RFC and on towards Second Crack(SC).
Seem to get much better results if the bean temperature is brought up gradually to roughly 150C and then slowly accelerated towards the onset of FC and as FC begins to get a nice roll on. The temperature is then backed off somewhat so that RFC is maintained but not increasing the bean mass temperature more than a degree or two per minute and as RFC begins to peter out, the temperature is increased again slightly so that the gradient settles on about 4-5C/minute until SC starts. Once SC snaps are regular (but not rolling) the temperature is wound down again to a gradient of about 1-second crack/minute until the start of Rolling Second Crack(RSC) at which time I pull the roast and immediately cool the batch.
I guess it seems like a lot of mucking around but the results are worth it in the end. I guess some of the problems with trying to push the roast batch too hard initially (using a Corretto) arises from the heatguns tendency to concentrate the hot-air blast to a very narrow stream and thereby risk scorching the beans on the outside before the internal structures have achieved the same rate of temperature rise. It doesnt seem to be as bad with "softer" beans though as these seem to allow for the transmission of heat quite rapidly through to the centre of the bean. In the end I spose, youll just have to experiment a bit with your setup until the results in the cup indicate that youre starting to nail the ideal profile for your palate.
Hope some of this is helpful mate..... :)