Another +1 for the OC-5. Why?...
TLDR: the OC-5 seems to give us both the OC-2 and the OC-3 pedals combined into one unit (and another reason for "5" = 2+3?) with improved tracking compared to both its predecessors and throws in an octave up. It's also been very competitively priced - you get a lot for your cash! What's not to like?
That OC-2 sound
As pretty much everyone else has already reported back on the OC-5 thread, it nails that classic "OC-2" sound with the -1 oct solo'd, which is great.
Octave-up
I didn't think I was going to particularly like or use the octave up, but I'm already won over. It's not a clean octave up in the way the Digitech Mosaic is, to give you an 8 string bass sound, but it definitely adds a bit "extra" when used with the -1 oct and a bit of -2 oct; both when the pedal is used by itself but also when combined with fuzz and / or filter. Easy to dial in a more 'Royal Blood' sound with a bit of clean (3.5/10), +1 oct (5/10), -1 oct (max), Poly setting at full range, pick into VTDI set for dirt.
Tracking
Very good at normal bass riff speeds, but will glitch if you sustain a note (which is not unusual for octavers). I actually prefer it in Poly mode over Vintage mode when I'm using both octave up and down simultaneously, as it gives me a cleaner overall sound and a touch better tracking.
With other pedals
Put it in front of a Red Ripper fuzz and Proton filter and it plays very nicely with them both, thickening up the sound just as you would want from an octaver.
Pricing
The OC-5 has been competitively priced by Boss at around £119 inc P&P. In fact, I can't think of another quality octaver that offers quite so much for such a good price.