well the growl knob is almost identical in tone to the oc-2's -1 octave. the girth knob which can be blended with the growl and the clean is a bit more of an aggressive less synthy octave down the than girth knob (or oc-2). i personally like the addition of the mid boost. it tracks about as well in my opinion as the oc-2, although some around here like the tracking of the oc-2 more. its also true bypass, although i think i remember the oc-2's buffer being decent. i love the oc-2 but personally prefer the bod for the variety of tones, mid boost and true bypass.
I must have tried defective BODs because I hated them. For tone, I prefer the OC-2 and I think the OctaBass sounds great and tracks lower than the OC-2. Except I found an OC-2 that tracks exceptionally well. So for me, the OC-2 rules followed by the bass octave on the Line 6 M9. After that, the EBS and OC-3 in Poly mode/guitar input.
IMO no pedal tops the OC-2 for the 100% octave down/0% clean "electronica" tone. The MXR's "growl" knob is pretty much identical tonewise but the Boss tracks cleaner and faster with fewer artifacts though the MXR does track a bit lower on the E string. Since that sound is the biggest reason I use an octaver, the OC-2 is my choice.
For synthy fretless sounds (ala Pino) I like the Boss but the extra features of the MXR like the ability to blend some "Girth" and the mid switch make it a more attractive option for me.
The EBS doesn't track as low as the MXR or with as few artifacts as the Boss but it is more forgiving of technique/accidentally hitting two notes simultaneously as the others. In all three modes it has a gritty but more "natural" sound than the OC-2 or MXR "growl" side and a more focused sound than the MXR's "Girth" knob.
The three modes give you a bit of flexibility with the Low being pretty fat and the Hi being somewhat synthy but unlike the two tones of the MXR its sounds are more alike than different. Still, the EBS is my favorite of the three for a "rock" octaver, especially when combining it with overdrive or distortion.
One other option is the Aguilar Octamizer which is VERY tweakable with well thought out features. It doesn't get the type of synthy octave down sound I want so it wasn't for me but it's definitely worth checking out.
as a previous user of an octabass, someone who has sampled the BOD and a proud owner of an OC-2 you see where my vote is.
Octabass: tracks well but too blah sounding
BOD: really dug the growl but the OC-2 tracks better
OC-2: it took me 2 but the second one tracks amazing with proper technique. its a MIT. I use it with 50% clean and 100% -1OCT. sounds beautiful and esp when you run it into a fuzz box it adds some nice balls to it.
