If you have a Boss TU-12, I don't see the need to get a peterson strobe tuner.
Yes, there are audible differences when using a strobe tuner - on clean, chords ring beautiful, on distortion power chords have more body/punch, there's a difference alright.
But worth it?
Up to you... IMO, if you have the $, go for it, else, the TU-12 will do.
If you have a TU-2, screw it.