I have one and love it. No false alerts on the roads I regularly drive.
I haven't hardwired it yet in my Elise, but have in my TT. Make sure you buy the extra $30 hardwire kit with the remote on it. You'll love it.
I figure for the Elise, I'm gonna either hang it from the mirror with a custom mount or make a bracket to hold it up next to my head like others have above the interior light. I've just been lazy and haven't created prints for the bracket I wanna machine to hang it from the mirror. Hopefully I'll do it within the next month or so and share the prints/outcome.