Didn't really underestimate it or overlook it, but Paul Durham made me two awesome slate over glass calls. I'm far from a friction call expert, but the two I have play very easy and kill turkeys. My 7 yo son has claimed one of them as his own.
Spring Allure Slate over Glass in Shedua is my go to. It's killed turkeys from the Carolinas to Florida, Nebraska, Kansas, and Mexico.