Did some quick side by side image comparisons with the files from the earlier speed test. I can't see any obvious difference in image quality. Possibly v6.6 has more sharpening applied by default but I haven't really fiddled away from the presets yet.
Comparisons between DXO and lightroom?
Never got into LR myself, but you can get a demo of both and try them
Canon 1D, 300D IR, 450D full spectrum, 600D, 5D2, 7D, EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 70-300L, 100-400L
EF-S 15-85, TS-E 24, MP-E 65, Zeiss 50/2 macro, Sigma 150 macro, 120-300/2.8 OS, Samyang 8mm fisheye