Your description of Tammy vs. E.G. is right on and I agree. I listened to her nightly in 1982 and really came to appreciate her voice and her style. She certainly isn't better than E.G., just different, but in a mysterious way. The plots in many of the later shows were more contemporary than the earlier ones. I guess just showing the changing times since the shows were largely written by the same writers through the whole series, i.e. Sam Dann, Roy Windsor, Elspeth Eric, Bob Juhren, G.F. Lewis, James Agate Jr.

For this particular episode, if I should critique, it was too predictable. Too much was given away in the intro so you knew what was going to happen. The acting and sound effects, though, really paint a vivid picture in my mind. My relatives have a cabin in the Rocky mountains of Northern New Mexico and as a youth we visited frequently. There is a lake or pond visible from the front porch and at night it was sometimes ominous (and very cold) outside. So this episode reminds me very much of our trips to NM in the late 1970s and early 1980s, right at the time I was listening to Mystery Theatre every night. 