Shift improver kits B&M and Transgo.

Most of us prefer the durability, control, and overall function of manual shift transmissions. I prefer them myself, however I recently installed a B&M shift kit in my 904 torqueflite (75 Valiant, slant 6). Let me tell you, for the cost ($90) it was worth every penny. This kit recalibrates fluid pressure, giving my car almost the feeling of driving a four speed stick. Not only do I get more performance, as far as response and speed, the gas mileage has improved too. Now, I want some opinions about these kits (if you have used them, you'll know how great an improvement they make on automatic transmissions). An automatic with a shift kit definitely outperforms one without, but how does it compare to an actual standard trans? Many pros and cons, just wondering what you all think!