I have room for one standard size pedal on my PT Pro. I am hovering around two options. 1.) Dr. Scientist Tremoloessence 2.) Boss PS-6 Harmonist. Neither pedal is a need, nor will they get used often. I play a lot of chords and do a lot of textures, so the tremolo is particularly interesting. I have also always wanted the pitch shifting whammy option, and the harmonist paired with my expression pedal would fill the bill nicely. I have the Zoom MS60-B, and the tremolo is pretty nice, but as a bonafide pedal junkie, I am wanting a real trem pedal with tap tempo. Thoughts?