Hall-effect switch or photointerrupter
I'm not hall sensor export but I can tell you I worked on a lot of consumer printers and scanners, and every time we did some kind of limit switch it was a hall effect.   So that's got to tell you something ;)

With a little online research I found this paper that talks about the hall effect and it's disadvantages.   They don't seem like they would negatively affect your project as you described it though.

Basically the limitations they mentioned are distance that the sensor works at (not really a problem for your limit switch), sensitivity change over temperature, and the presence of an offset voltage.   Again if you're just detecting when something hits an edge I'd guess it wouldn't be a problem.

Here's the article:

http://tec.upc.es/ie/transp_2010-11/HallEffect.pdf