i too, own a fastrax tool, as well as a magnetic hub "old school" caster/camber tool i got from speedway motors. both are quality units, and precise.
i restored a set of turn tables for setting toe. these tools sure beat paying $99.00 a clip for alignments, and have paid for themselves many times over.
whatever tool you decide on, you will have to practice a little to get repeatable results, but it is worth it in the long run.
also, make sure you treat these tools good, as well as store them properly while not in use.