All the guys flying RC Turbines use EGT to keep things in check. As a former military pilot, we used it as a measure as part of the engines performance. If it got to hot, then it required an inspection.What they have on the market now are little temp guages.

They are of no value to planes because there are no set guidelines but pilots like to use them to show they think they no something others don't.

On the other hand they are very useful in the R/C car area.