The quote isn't exactly true. Pumps don't overheat with too much head loss, they are more likely to overheat when head loss/pressure is too low and the pump is close to run out. Also, there is no such thing as "maximum plumbing flow rate" but there are recommendations. Water will move as fast as a pump can push it. So a larger pump will always produce more flow rate and theoretically, there is no limit other than pump size.

Also, an AG pump usually does not have the suction lift that a IG pump does so priming can be an issue if your pump is much higher than your pool. Also, they tend to be low head pumps which can have significantly lower flow rates when used on a IG pool with long runs and/or require lift for solar heating on roofs. I would stick with a IG pump.