I have owned and tried all three of them. Actually twice I've owned an Eternity and an OCD, and I had a Timmy and a Dano Transparent OD (Which is supposed to be a clone of a Timmy).
I think they're three entirely different pedals.
The OCD is supposed to emulate a Marshall 18W. It's a very open sounding pedal with a "wet" character. Sort of rubbery, hard to describe
Had a version 1 and a version 3. Think it has way to much bass for my taste. Can't really dial that out. I think it sounds best with the LP setting and the gain fairly low. Can be bright also.
The Timmy is more transparent as everyone mentions. It has a drier character. A little grainy. Good eq possibilities with both bass and treble knobs. I usually want a little bit of mid and I have a hard time dial in mids with the Timmy. You get a little more with increased gain. A good pedal that's supposed to be designed to be used with a Marshall Plexi.
The Eternity is the most midfocused of them. It has a great range of tones from clean boost to medium overdrive. I don't think it's too bright. The tone knob is a trebleboost so if set at 7 o clock it's not bright. Can be extremle bright though with tone at 5 o clock A bit more compressed then the others. A great pedal with singlecoil. I prefer it for leads but can sound good for rhythm also. But I prefer my KoT for rhythmtones, which is a more open sounding od.
I use Telecasters and a Blackface Vibrolux reverb.
Just my two cents....