I am not well versed in this stuff but I thought the 4221 sounded like it might be a good fit in my own case (don't have one yet), cheaper than the 4228 and it seems like it doesn't need to be aimed as precisely. I managed to find some other graphs from the hdtv primer site that seem to give a visual idea of directionality:
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www.hdtvprimer.com/ANTEN ··· 228.html»
www.hdtvprimer.com/ANTEN ··· 221.htmlEdit: the page on the 4228 seems to be on an older version of the antenna.
Another thing I was wondering about when someone mentioned cable loss, what about using an ethernet based tuner like HDhomerun and mounting it near the antenna, say in the attic or in some kind of outdoor enclosure?