I have also empirically found that larger roundovers make a difference. I built a pair of speakers with 90 degree corners (no round or bevel), and then I made some add-on roundovers that can be installed or removed in a few seconds. The larger the radius of the roundover, the better the sound. It is more natural, lifelike, and the imaging is better. Without the bevels, the sound made me cringe slightly. Especially when removing a large radius, as the change is immediately apparent.
Note, the effect is subtle, and people not used to evaluating speakers probably won't even notice it. It is a higher order effect that can be used to extract maximum performance from a speaker.
It has been very interesting to experiment with different radii on my speakers, and I would encourage some DIY'ers to try using different setups just to see if you can hear the change.