Looking for a decent digital tuner--and one with "Add Digital Channels" feature

[Old1625]

I live in a rural deep fringe reception area, where television stations have to be picked up from all directions. I have to change antenna aim frequently when hopping from one station to the next. I need a digital tuner that is decent in performance, and has the feature where you can add more digital channels as you change antenna aim. Most of the tuners I've encountered--be they built into flat screens, DVRs or free standing--do not have that feature, and whenever the antenna is re-aimed you have to go through a scan procedure where only the channels you can now get with that particular antenna aim are programmed, and all the previously programmed channels are erased. I also find that dealers generally don't know whether or not their product will have the needed feature, and many are reluctant to open a carton to retrieve the user manual so such can be determined.

Any suggestions as to a really good tuner...?