Okay, here's what I have found out so far:
The minimum discernable signal (MDS) levels - or sensitivity - for all tuners wasn't that different. The SAT-HD100 is actually quite sensitive. With the 7 UHF DTV channels I received, it was as good as or better than the Samsung SIR-T150 in holding a weak 8VSB signal. (Typically -85 dBm was the lowest possible signal, vs. the Samsung's -83 dBm).
The fastest tuner - by far - in locking up a valid 8VSB signal was the Samsung SIR-T150. It locked up some signals as fast as 1.5 seconds after changing channels. The Zenith and Princeton tuners took as long as 4.5 seconds to recognize and lock up some channels (or display a multi-channel stream on the channel guide).
In signal headroom tests, the Sony once again was the best tuner on four of the seven channels, while the Samsung took top honors on the other three. Headroom is defined as how much an 8VSB signal can be attenuated once it is captured, before the signal starts to drop out.
The Sony tuner had a 1 to 6 dB advantage in headroom over the other tuners, depending on the test channels.
Contrary to another post in this topic, the Sony did display program info from the three stations that were transmitting it. This included the virtual chanel, program title, and a short description.
The Samsung tuner also showed a program title where available. Both tuners activate this function from a button marked DISPLAY on the remote.
In some cases, the station had the wrong data up. On Fox, a cartoon came up with "NFL Football" as the program data. Later on, "Ally McBeal" came up over another cartoon.
All the tuners seem to run moderately warm - not hot. The Sopny fan never shuts off (annoying, as many have noted) and the Zenith's fan is quite loud, but shuts down when the tuner is powered off. The Princeton and Samsung tuners do not use fans, but don't seem to suffer for it.
I have not observed any audio dropout on any of the tuners. However, the Sony tuner did have considerable difficulty trying to lock up on a station transmitting the PBS satellite "80-3" PSIP. The SAT-HD100 did recognize the PSIP data, but was never able to lock up the picture. All other tuners locked up this signal right away.
I also observed a strange "posterization" effect on the Sony when receiving some signals with moderate multipath. It's as if the picture solarized, and could only be corrected by switching channels.
The Sony refused to decode any digital audio from the local Fox affiliate. The three other tuners had no such problems.
I will try to post more details from this test soon and will let everyone know the URL for the test results.
KC