@Andrew. Bruce has posted some excellent reports on irons and I would consider his opinion definitive. You might also want to consider hot air guns, though not the one I reported on some months ago – this is one of many cheaper tools that don’t regulate the temperature and should not be considered.
Of the three ranges that Steinell make, their professional range is aimed at people repairing car bodies and the like. They all regulate the temperature properly, are light and quiet with durable ceramic heaters, and one has a display allowing you to monitor both the temperature and air flow at any time.
These are only a third of the cost of a Leister or Seivert barrel-grip gun, and have nozzles for other jobs like thawing frozen pipes, soldering new pipes, stripping paint, lighting a BBQ, fixing your kids’ broken toys etc etc. So there are many ways to justify the cost.
I see two benefits to hot air: 1/ it heats the coating with only residual heat getting into the fabric, thus reducing heat stress. 2/ it heats the coating uniformly – where an iron may make patchy contact on curves or an uneven former and leave colder spots that may be poorly welded, hot air will be consistent over the whole target surface.
Just a thought.