I've been using Heat Shields for the past ten years or so. They work great, but I've had some that delaminated fairly quickly just from routine use.
I like them because I don't have to purchase a bunch of generic brands to find one that fits. Plus, on the off chance that I do find one of these that fits, when I go to find a replacement the brand is usually out of business.
So the extra cost of a custom fit shade is worth it to me.