Don't be so sure that there's much corrolation between accuracy and price. There are two major things that impact accuracy... time base accuracy and spacing of the sensors. Since the sensor spacing is fixed in a one piece unit with the prochrono, it's going to be accurate because of the cheap design.
I haven't worked through the math, but I don't think you need an atomic time standard to clock one of these things. Think of your basic quarts driven Timex. It's easy and cheap to make a pretty precise quartz timebase.
When it comes to remoting the display, I'll just pop for the optional remote.
The CED M2 has a much better feature set than the cheaper one. It's worth the extra money just for that. Doesn't make it more accurate, especially when sensor spacing is reset every time you assemble it. if there's some engineering info out there, instead of just sales hype, I would be tickled to read it.