1. I have yet to see a shotgun heat shield made by a company or in a manner that I respect. Old Army issue trench guns would be the exception. I am sorry but most of the heat shields I have seen are from bottom feeder companies and just look like cheap pieces of crud. Even if I did want one it would not be one of the ones I have seen in the cheap / tactical crud department of gun shows and shops.
2. Given the low quality of the products offered I would have greater fear of the unneeded thing failing at a time when I needed it and somehow jamming the gun than I do of somehow burning myself on the barrel.
3. The chance of anyone civilian or LE outside of those in combat overseas, EVER firing a shotgun in defensive use to the point of needing a heat shield is about on a par with worrying about getting hit by a falling meteorite.
4. Personally I view a hot shotgun barrel at the range the same way I view a revolver cylinder gap. SOmething to be aware of and avoid injuring one's self on.
5. Too much tactical crud on a shotgun only makes it more heavy, and more stuff to break or get in the way. Sorry but nothing makes me run the other direction quicker than a overdone shotgun. Keep it simple and useful.