I found out about the nudge up and nudge down key bindings, but this will only nudge by a semitone. Would there be another way, then, of selecting notes in the PRV and instantly shifting it up or down an octave? Perhaps some .ini wizardry of some sort to change the amount of semitones of nudge up/down? Cheers.

Not in front of  my DAW at present but if you look in the track inspect clip tab there is a transpose function there.

Hmm maybe I'm being dumb but I can't see what you're referring to. There's no such function anywhere in the Clip tab of a midi track's inspector, nor within the inspector itself. I'd be looking for a way to do it with a keyboard shortcut anyway, like it's possible in ableton live.

Highlight the note(s), then top of the screen choose 'Process' and then 'Transpose' from the drop down.
Sometimes I just highlight them in the PRV and drag them up or down with my mouse.

I know, but that's the thing, that's quite inconvenient when I want to experiment and quickly try out a bunch of different chords. Anyway, by now I don't think it can be done, I looked everywhere, unless the semitone amount of nudge up and down could somehow be modified. That should be in the nudge options, really. Might have to submit a feature request on that one.

Select notes and enter "+" or "-" followed by "12" in the Pitch field of Event Inspector.

I am not in front of my DAW but I seem to recall in 8.5 you could put a midi transpose "fx" in the fix bin so that it automatically transposes for you, even "on the fly" as I recall

I am sure this feature would remain in x2 so I hope this sets you off in the right direction

It'd be nice if there was a simple keystroke to transpose up or down an octave, but there isn't. I use Jlien X's method: simply typing +12, +24, -12, etc. into the "Key+" box in the track header.

Create a CAL script and bind it to a keystroke. Here is a script for raising up an octave. Cut and paste between the --- and save as "Octave Up.CAL" where all your CAL scripts are stored. Then add a keyboard shortcut in preferences. If you need help with Octave down let me know (hint: change the += to -= and save file under another name):
---
;; Octave Up.cal
;;
;; This is a sample CAL program that implements an editing command to
;; raise notes up one octave.
;;
(do
 (forEachEvent
  (if (== Event.Kind NOTE)
   (do
    (+= Note.Key 12)
   )
  )
 )
)
---

Not sure if this is what you are looking for but you could use the Event Inspector. All you have to do is lasso or multi select the notes you want to change, enter the pitch info and it's done. Here's a digifreq vid showing it being done. http://www.digifreq.com/digifreq/video.asp?ID=7