Any weight cutoffs limit the scope of your article and bias the results. Your definition of acceptability for "SUL/XUL" solo shelters is 20 ounces, a clearly arbitrary number and one which excludes many comparable choices (as you disclose). Why 20 ounces but not 16 or 24 or whatever and why do you punt on the issue of trekking pole weight if such poles are needed for setup? At the end of the day, 20 ounces is an arbitrary number which is fine but it's your list and your definition alone. Same will be true for 32 or 48 ounces or whatever arbitrary number you choose for two person shelters. My point is that ultralight or SUL/XUL, whatever any of those terms really mean, is all in the mind of the user. All shelters are compromises one way or the other and when you filter by weight you also filter by design and features and price.
IMHO, a much more interesting and informative comparison would be one that also delved into usable volumes, performance usability including setup times and setup/takedown in the rain, ease of entry/exit, and $/ounce compared to other choices etc. Weight is but one of multiple considerations when choosing a shelter and if all you care about is weight then you are compromising yourself and, very likely, your wallet. A Contrail, for example, misses your target by about 5 ounces but it's half the $/oz--in most comparisons 1/5 or 1/6 the $/oz--of the shelters that do make your list. Does that make the Contrail better? Absolutely not but it gives some perspective. Two person shelter lists will suffer from similar comparison shortcomings if all you care about is weight.