I agree with the antenna suggestions teleview has made.
Like you,
I'm a fan of the HDHR. You obviously have your HDHR up and running, so I have to politely disagree with the suggestion that you transition to a less flexible boxed solution. The HDHR is the best consumer grade signal meter and antenna alignment meter I know of. If you choose to add a second HDHR, you can connect it to the second antenna system, making both antennas available to any iPad or PC in the house, that's more reason to stick with it.
For traditional TVs, the A/B switch is simple, inexpensive and reliable. A premium alternative to the A/B switch in a two antenna home would make use of the STB tuner/DVR...
http://forum.tvfool.com/showthread.php?t=2882
My personal experience with the DB4e has impressed me. Antennas Direct appears to have refined the 4-bay to take full advantage of the narrower range of UHF channels now in use. Higher gain with wide forward beam is a handy combination in many locations.