I've found the 1302 to be the least useful of the Alegro sensors. The sensitivity on them is 1.3mV/Gauss, so take nearly 180 deg of a strong magnet for a full voltage swing, at least with the Bic pen arrangement. The A1301 behaves the same but can use half the magnet, at 2.5mV/Gauss which allowed me to implement some miniaturization.
Here's the post I made a while back about miniature DIY sealed Hall pots (I think of them as gen 2 versions of Gene's), which are easy to make and incorporate into controls projects. DIY Sealed Miniature Hall Pots, on the cheap!
Since controls don't typically move 180deg, this rules out direct mounting and tends to waste usable range of motion/resolution. Lately I've experimented to good effect with A1324 (5mV/Gauss) and have found them to be most suitable for typical controls, only taking about 90deg for a full swing, allowing direct mounting as well as better utilization of available resolution.
That said, I've never had any problems with drift with any of my Alegro's. I only buy them from reputable dealers (Newark Electronics in my case) however, because I hear ebay and other sources are full of sub-par counterfeits.