I live in North Carolina and had a Laser Interceptor, V1, and Bel STI-R+ installed in my previous car, a 2010 Audi S4. My LI's were useful exactly 2 times in the 2+ years they were installed, and both times I saw the cop before he actually hit me with laser. Laser is just not used much in most parts of the state.
When I bought the M3 I only re-installed the STI-R+ and V1. Holding off on the LI's for a while to see what develops.
2012 X5: BSM/Black/Sport Activity/STi-R+
(Sold) 2013 BMW M3: JZB/Black/ZCP/M-DCT
(Sold) 2010 Audi S4: Deep Sea Blue/Black/Prestige/S-Tronic
(Sold) 2006 BMW 330i/Jet Black/Black
(Sold) 2005 Audi S4/Moro Blue/Black