I used this product all of last chase season.
I too have wondered about the low profile affecting the reading, but found it to be pretty accurate to my current driving speed, although it took me forever to figure out how to get the display unit to read MPH.
I had the problem with the cups breaking off at first and I gave up on it, till I was alerted they designed a stronger cup [thanks to Bill Doms] I was sent 2 of them for free, again Mr. Lorenzo is very understanding and wants to make sure his customers are happy. So far this new cup has lasted...well see how they hold up in '08
Here it is pictured on my roof in case anyone isn't familiar with it. This is in the OK panhandle on 4-21-07
and again on 10-18-07 with the new visual vane option.
A word of caution, replacing the cups is a true test of ones patience, it requires the removal and replacement of a really small c-clip...I cant even begin to describe the frustrations with that thing!
I would recommend it, they're small and affordable and a good way to start, and until someone can proove the readings are way off, I have no reason to question the accuracy.