[DavGoodlin]

Jr Tech: The Calculation of the coverage area appears to overstate the coverage of the VHF channels when compared to the UHF channels.

Well stated and quite true!

The ATSC (8VSB modulated) signals seem to behave very differently, especially when subject to terrestrial challenges and weather variations. My personal example of the contrast here is the signals from Baltimore, 50 miles to the SW of our gently-rolling, open terrain. Philadelphia, 55 miles to our East has two VHF and ten UHF stations but requires a decent rooftop antenna. This is in addition to 7 "Harrisburg market" (2-VHF, 5 -UHF stations) received with a medium-sized, attic-mounted antenna. Rotators are much less helpful, since the local channels come in no matter where the antenna is aimed.

The Baltimore example....

Analog: VHF channels 2, 11, 13 were fairly stable while UHF channels 24 & 54 were weak, yet 45 was fairly good (like the VHF's) due to a higher antenna and power than the other UHF's.

Digital: 11 and 13 retained (and returned to) their VHF spots, but cannot be received most of the time, even with a VHF log-periodic rooftop antenna and booster. WMAR-2 is on UHF-38 (using a new antenna and transmitter no doubt) and easily received, even with a modest UHF rooftop antenna.
54 (DT-40) and 24 (DT-41) are a bit weaker but still consistently received. 45 (now on 46) is rarely received although the transmitting power and antenna height are unchanged.

Now we change to a very different location at a hunting lodge along a creek, "upstate" in a deep, wooded valley between Binghampton NY (50 miles away) and Wilkes Barre (37 miles away);

Analog: VHF channel WBNG 12 from Binghampton was fair using a HB-VHF 10-element yagi, no other channels were received.

Digital: VHF channel WBNG-DT 7 is fairly reliable and WICZ-DT 8, also from Binghampton at much lower power is received a majority of the time. No UHF channels from either city were received, even while using a Winegard 7694 and booster presumably due to the deep woods.

Note: Electronic ballasts in T8-lamped fluorescent kitchen lights must be switched off when watching WICZ.

Conclusions: VHF seems better suited to areas with severe multipath but the range seems poor over open terrain. Weather affects VHF even more than before. Less signal strength is required to "acquire" DT reception, so UHF performance seems better, at least in more open areas not subject to much multipath.
DT recievers (HD sets and converter boxes) seem to have much less interference rejection that analog stuff did. Electronic ballasts, especially for higher-wattage compact fluorescent 3&4 tube fixtures really cause problems similar to weak FM stations. The screw-in CFLs are lower power and thus not much of an issue.