I am using the ChannelMaster "Extreme80" (quad bay) at the beach and it works great because all the towers are generally within the direction and range. This antenna is mounted on the roof but the height is only about 18 feet.
I am using the ChannelMaster Omni+50 at the main house since the quad bay would not work there (towers are way off in different directions), and other than needing to be mounted higher, it too is working great. This antenna is mounted using an old DTV sat mount, and is on an extension pole so it's up around 38 feet.
I have a client where there are two quad bays run into a splitter/amplifier and they are mounted at 40 feet. Didn't know it would work since you couldn't do this with analog antenna's but with digital it seems to work fine. This was done in the area of my main house, again due to the way off axis towers.
Use antenna web to find out where the towers are and go from there. Also bear in mind the antenna may not work worth a bean but if you move it laterally it will all of a sudden work like a champ (the wave can get you).
