Here is Channel Masters product description:
CM 4228HD Product Description
Frys product description does not match the manufactures information. Channel Master claims only UHF channel coverage. I'm sorry that you have ill informed sales people leading you down the wrong path.
The CM4228 and similar antennas are sensitive to aim, but not nearly as critical as a parabolic dish used for satellite service.
NSAA's suggestion of the HBU33 in your attic strikes me as the best option for you. If you have problems with reception in your attic, the HBU33 is going to serve well if you move it to the roof. You can purchase through Radio Shack, but they tack on a huge markup. I would have the confidence to buy direct from the Antennacraft web site even if they prohibit returns... But I can't make that choice for you.
I presume that you get a significant snow load on your roof at times. If so, that will likely be the most difficult condition for an attic mounted antenna in terms of signal attenuation. My preference would lean heavily toward a tripod or chimney mount... But again it's your choice, not mine.