I use IERC tube shields on just about everything they will fit on. I did some reading/research a few years ago and they seemed like a good thing.
Yep - they're ugly.
As you might imagine it's a bit boring here in lockdown town and I decided to throw a different set of tubes at the Odyssey Audio pre. It uses a set of 12AU7's.
So cover off, grabbed the IERC shield and got reminded that tubes get warm! Used a cloth to pull the shields off and then...just for fun...touched the tube. Darn thing was warm but easily removed with fingers.
And that's the way those things are supposed to work. I just never tested the theory. Cooler tubes should last longer and the EIRC shields definitely pull heat away from the glass. I tried the same thing on the Crack headphone amp multiple times and found the same result. The shield is HOT, the tube is NOT.