[Yetiman]

Yes, it does pick up RPM's with an MSD unit in the car (You have to calibrate it, but it does work).

Mine was very useful for improving my launch technique, and showing what helped and hurt my 60' time was especially helpful.

Having a nice stretch of tarmac to use over and over helps too. I use a one way access road along the freeway near my house that has room to do an 1/8th mile and have plenty of space to slow down and brake with no driveways and an 8' fence the whole length of it. It also helps that there aren't any houses anywhere along it (parking lot to a fairground).