I would feel lost without having both at all times.
The Dexcom and canula from any pump should be at least a few inches apart (I forget the exact number, probably 3 or more). I wear my Dexcom on the side of my abs, and the pump either on my arms or on the front of my abs. The only real difficulty I've experienced is that with the pod I had to adjust my sleeping habits a bit, being mostly a side sleeper, if I would lay on top of the pod it sometimes caused problems. Though with the newer smaller pods, that not as much of an issue now. But with two devices, I sometimes have them positioned where sleeping on my back in the best way to keep both safe. I'm getting used to it, and it is well worth it to me. I also had the "two devices!" phobia, but got over quickly once I found how well the Dexcom allowed me to control things.
I use both and couldn't live without either. I keep the dexcom in my pocket and i carry the omnipod PDM with my cell phone. It would be nice to have them integrated but it's not going to happen anytime soon.
I started pumping in 2001. My doc discouraged me from a cgm when I asked. I now have a new doc and they let me borrow the dexcom 7 for a week and I loved it. Right now I use the Omnipod and Dexcom G4.
The CGMs are getting better all the time. When I tried the then current Dexcom in 2011 it didn't work at all for me, but two and a half years later the latest versons might.
I have used both for the past several years. I check the Dexcom several times a day, both to calibrate and just see the current level. I find it especially useful when I am about to go out on a walk or some other activity where I might need to take along some extra carb in case of lows. The Dr. finds it useful in my general diabetes management. I have had nothing but success with the Dex G-4 and it's predecessor. It would be great to have them combined as one unit but I am grateful just to have the technology available to help keep my diabetes in good control.