Here is the kit I'm reviewing:
http://www.summitracing.com/parts/BMM-70244/
I've had this installed for just over a year now. Of all the lockup controls I found, this was the only one that allowed me to change the lockup point on the fly. Install was very simple. No access to the tranny pan required. Just plug and wire it up. My biggest problem was finding a brake switch with two terminals. I think I went with one out of an early 70s camaro.
The lockup controls stay with you in the cab so you can make adjustments as needed. Once you set your lockup MPH, I highly recommend you stash it under the seat or someplace out of the way. I found that constantly handling the controller will cause the wires to pull from the connectors. That's my only complaint. B&M used very weak wire connectors. I've had to rebuild mine at least 3 times. That's because I always unnecessarily fooled around with the controller. After the last rebuild I shoved it under the seat and it's been good ever since.