I have one and it works pretty well. It needs to be setup properly and it will not be nearly as accurate as a TrackMan.

If all you are looking for is a device to look at the deltas when making club or swing changes it is a good tool. If you want absolute numbers, it may not be the best.

I use it to see changes when working with students. I take some baseline numbers (and assume that they are not precise). Then after the swing change settles in, take more numbers and compare.

It is also useful when club fitting. Take baseline numbers with the existing clubs and get new numbers with different club setups.

I can only comment on the ES12, but it has been great at dialing in my distances!
as far as swing data I like the sky pro which offers a plethora of valuable info and training modes.

I have the ES14 and compared it to numbers on the Trackman when I purchased it a couple of years ago. I found it was not entirely accurate and there were considerable differences when compared to the same shots on the Trackman. I also found it was more accurate on irons than on the longer clubs (hybrids and woods). It is very important too that you follow the instructions and guide when setting up the unit. I did find that the differences between clubs (i.e., the delta on the ES14) was similar to the delta on the Trackman. Bottom line, it is a useful tool but you get what you pay for. Mine was a tee gift at a golf tournament so I did not have a lot invested.

Thanks for the info guys!

Cheers,

Dr. K