It just seemed like there was a LOT of extra tweaking I needed to do for each image. My suspicion is that if you want to use DT (effectively), you need to have a deep understanding of color theory and image processing (at least more than I am willing to devote).
I also enjoyed his rant(s) on the new releases of DT, especially the complaints about the UI.
I never tried RawTherapee.
This is what I use, too.
I did a lot of side-by-side comparisons between C1 & DT on my raw files and I could not get DT to make anything that looked like C1's automatic adjustments.
The best I could determine is that the out-of-the-box adjustments made by C1 were somewhat complex (e.g., it wasn't a 'simple' transformation of rgb values).
Obviously, it's preferable to know what's happening under the hood instead of relying on black-magic, but I just didn't have the time to invest in trying to figure that out.
C1 is really nice. I also compared it to Lightroom and I didn't like those results as much as C1.
edit: Although C1's masking features are excellent, I wish they had more parametric masking features. That's the one thing I miss from DT.