Spent a considerable amount of time with the DCX pedal in various situations to get a feel for what really works. I used it extensively on the EQ side and the OD side. It's a good pedal, and does exactly what it says. Let me explain.
First thing to consider from the EQ standpoint is the pedal is labelled correctly as a TONE SHAPER. It is in no way a surgical EQ. If you are looking to replace your EQ pedal or your other preamp, this is not the pedal. If you want to add character, primarily the character of the 610 it does that really well. If you approach it from that standpoint it can be very useful.
There has been discussion of where to place this pedal. It seems to have worked best for me before the compressor or solo directly to the amp. The EQ controls are not for fine tuning. The LF control, even all the way cranked its still usable. It doesn't give you the low 40hz bottom you get from other eq pedal (not a bad thing). From what I could tell this weekend, it does seems to work better with a 4 string passive bass. And as you would expect, it sounded great with a P bass with flats.
The OD section is a different story. I really think this is where the pedal really shines and can be useful for most people. OD and compression are very personal and there are many right answers for this. The OD sounds good on everything! That being said, my favorite overdrive sound of the weekend was the DCX going into a compressor into the SVT bassrig. It cut just right.
Overall, its a good pedal. It's not a desert island pedal, but more of a really nice dessert to your meal. Is it replacing any of my preamps? No. With the SVT bass rig and gives me a variety of tones. Really used it primarily in EQ mode to give it an old school sound. With the 64 Bass rig I did just the opposite. More overdrive into a cleanish tone.
Where do I see it being most useful? In Ear situation where you have a wide playlist including 60s/70s music into your favorite pre or primarily as an OD. If you have a preamp that is more surgical in approach, this would be ideal to go in from of it for more character. For example, the Berg Super Pre would be a candidate to go in front of this pedal. My main concern on a situation like this is how does it really fit in the mix at a gig. I think this pedal does this well if you are clear on the intent of the pedal (or at least what I think they were trying to accomplish).
YMMV