Sorry, I don't keep up with antenna products and only know just enough about their design to DIY simple stuff, but back when I was serious into OTA AM/FM stereo and analog TV I had a similar pattern that only a large rooftop antenna similar to the CM-3679 w/rotator could pull in most of the stations well, though no doubt being across from PDK was at least partially responsible for the need.
Even then that was before the trees grew really tall/full, so swaying trees could be a problem with the higher frequencies [shorter waves] now that antenna height can’t exceed 10 ft above the highest roof peak.
This has become such a problem for me lately that I’m considering experimenting with some shielded omnis strapped to my tallest tree to do an end run around this regulation if I can figure out how to do it cheaply.
You can try doing what I currently have in the attic, it’s cheap, easy, though you’ll probably need a third [or maybe even a fourth] coat hanger one to get more omni coverage: http://www.avsforum.com/t/384623/atlanta-ga-ota/3030#post_22307537
The antenna is basically a CM-4221 minus reflector. I tried reflectors, but offsetting the antennas several feet arrived at empirically and aiming them individually worked best overall without any obvious ghosting/crosstalk, though in your case it may be better to just place them in a pyramid [or square if four] shape with reflectors: http://www.youtube.com/watch?v=EWQhlmJTMzw
Only one way to know for sure unless you know someone with the test gear/skill to measure your actual signal polar response in the attic, then use software to sim various designs to see which matches up best overall.
With no HDMI, I have no HD capability of course, yet ignoring fast action, my PQ is often better overall than my neighbor’s ‘HD’ feeds, with a wider, deeper stereo sound-stage on many stations to boot.
Anyway, there’s lots of DIY antenna info/designs on the net and various forums if you’re determined to stay off the roof and well worth the time/effort to pursue them if your local DSL, cable service is as crappy/expensive as my options are.