I look at it this way, how easy is it to break a normal hydrometer and how much will you benifit from owning it.
For me it's a waste of money
Primary: cabernet sauvignon, El dorado pale
Seconday: Golding abbey, Flanders Red, Cocoa IPA, S.C.A. IPA
Bottled: Golding kolsch, Raspberry Mead, Berlinner Weisse, Caliente Pale ale, Amarillo/Citra wheat