You've received some good advice (and some not-so good). Unless you want to watch 24 hour infomercials or watch the static slide of a Spanish-language religious Franken-FM station, low-VHF is pointless.
The C5 is best described as a medium to long range high-VHF and a short to medium range UHF antenna. Of course, "ranges" are all relative and are suggestions given to try to relate an antenna's performance with a reference that a typical consumer might relate to. It's highly imperfect, but it's not going to go away from any of the antenna manufacturers.
Given your TVFool plot, I'd say the C5 has a fair chance of being successful for the DFW stations. If you were calling in, I'd strongly recommend that you be prepared to add a separate UHF antenna such as the DB4, C4, or 42XG be used in conjunction with the C5.
You have several options open to you:
1) You could use a small-to-medium 7-69 combo as was suggested for full coverage of your major stations. This will be a traditional type of antenna.
2) You could select a UHF antenna such as the DB4, C4, or 42XG. This will probably cost reception of WFAA and KFWD. These two stations are the only ones that REQUIRE high-VHF capability (KTVT simulcasts on UHF channel 19).
3) Go with the C5 and be prepared to add the UHF antenna should it be needed.
FYI, the tech data sheet for the C5 (written by our design engineer) is located here:
http://www.antennasdirect.com/cmss_f...20with_uhf.pdf
A tip sheet for using the C5 and a UHF antenna is available here:
http://www.antennasdirect.com/cmss_f...werpoint_2.pdf
Anecdotally, I got a message this week from a customer in Frisco who has his C5 in his attic and has excellent reception. He isn't the typical user (he has his own hand held spectrum analyzer/signal meter) and posts on other forums his results of various antennas.