Dishpointer does work very well. What is is worth depends on your use. If you are an installer doing daily dish alignments, it's worth it. If you are like me, a hobbyist who only once in awhile needs something like that, it probably isn't (although I did buy it).
For the one-off installation, dishpointer.com is fantastic. To take it on the road would be, as you note, cumbersome.
Of course, a compass, inclinometer, map, and other "old fashioned" tools work great too.
