The HD8200U has as good or better CH-7 performance... on paper. The two are close enough that one could try though. If that fails...
The Y10713 lends itself to stacking. If done correctly, some additional gain and directivity can be had. One could hope for an additional 2 dB when stacking two. If stacking four, you might net 4 dB gain over a single antenna.
http://forum.tvfool.com/showthread.php?t=1024
You need to have an understanding of impedance matching and basic antenna theory as well as the skill, tools, time & money to put into such a project.
If you are up to that sort of project, you might as well consider a custom built antenna. Rhombic antennas promise a lot of gain, but they are too big to rotate. Aiming is critical.
http://forum.tvfool.com/showthread.php?t=2865
There's an active group of antenna designers and builders over at
http://www.digitalhome.ca/forum/forumdisplay.php?f=186