1) Though some members have an interest in DIY antenna construction, most are interested in a reliable off the shelf solution.
2) When dealing with VHF channels 2 through 6, there are several sources of RF noise/interference that are not as much a factor for the High-VHF and UHF bands. For example, the RF noise produced by a compact florescent bulb falls mostly in LF, HF and lower VHF spectrum. Only a very low level of noise is produced at frequencies in the high VHF and UHF ranges.
The The NM (noise margin) value presented in the TV Fool report is not adjusted to account for noise other than that produced in the antenna terminal impedance.
http://en.wikipedia.org/wiki/Johnson...3Nyquist_noise In the case of the UHF band, this is close to actual conditions. When dealing with VHF you'll need to consider the effect of noise in excess of the theoretical minimum.
The end result is, a higher gain antenna will be needed for reliable reception of Low-VHF signals than would be indicated by the unadjusted NM figure provided in a TV Fool report.
3) Attics are less than ideal locations for RF reception. The antenna is shielded from the desired signals to some degree while being closer to noise generating devices inside the home. So, if spec'ing an attic install it's prudent to recommend a larger, higher gain antenna. A simple dipole VHF antenna can work in some applications, but you need to consider the various factors that may call for a larger antenna.