Stamp,Few if any of those clones are meant for deep to deepest fringe areas so I don't think any built-in tilt they offer will make much of a difference in typical urban to fringe usage.
I do have excellent results from my 4221 HD clone. As you know living here in London, On; I am like 95 to 110 miles to Americian DTV signals. My newest setup has two connected together with one towards Detroit and the other at Cleveland. They are connected together by two 30 inch identical RG6 cable to a splitter (3.5 dB per side) used backwards as a combiner. I have spaced them about 29 inches apart. With the one pointed towards Cleveland, I do not use the built in tilt feature (it's crap) but I tilt it about 10 degrees back from 90 degree position. This produces nice results but not for reliable everyday watching, as you my already know.