Besides the shape, the panel antennas are designed as UHF only antennas. The advantage of independent aiming of the UHF and VHF antennas is not critical in your case if you can mount outdoors in the clear. If you choose to attic mount the flexibility of separate antennas may or may not be needed.
I concur with televiews suggestion of the HD7696P aimed toward 60° if you mount outside (which we both agree is ideal).
The only caution I would would offer re. A/B switching of a two antenna system is that
some televisions lack the ability to 'add scan' or manually add channels. If you have such a TV, it will forget all previous channels each time you scan to learn the available channels. This would make an A/B switch impractical due to the need to rescan the TV each time you switched antennas. If you have such a TV, consider this alternative:
http://forum.tvfool.com/showthread.php?t=2882