RokGoblin, I think you didn't get the Boncuck's point: At low motor RPM (low airflow), is fine to select a low temperature setting for the heating element.
But there is always a chance to select the powerful setting and cause a catastrophic failure. The only way to do it right is using a PIC, that would be always controlling the heat and the airflow, maintaining them into the limits, and also meeting the user requeriments. It gets too complex when cheaper and better-built alternatives are present.
I'm also a "modder" (ugly name I think) and I share your point about the DIY fun. As Boncuck said, use a light dimmer to control the heating element, and attach a simple digital termometer on the barrel of the gun to get the desired temp. If you need less airflow, put the gun far from the target.