I've been hunting for the perfect OC-2 ish thing for my board, and eventually decided the only way to figure this out was to gather as many of the options as I could. After some discussions on the 3Leaf and OC-5 threads I ended up filming some of the comparisons in the hope that it can be useful to someone in the same situation as me.
The options available were:
Boss OC-2 (the old faithful)
Boss OC-5
3Leaf Octabvre Mk1
COG T-47 (2x T-16) (the current incumbent)
Markbass RAW Oct