The evidence from espresso lovers suggests that conical grinders tend to perform better than flats; with the advantage becoming more obvious as the roast level gets lighter. This is also true for regular brewing.
The DRM hybrid burr set I tested in the M3 (see "The Bench" section) does all its grinding in the flat section, the conical section only acting as an augur to crush the beans as they enter the flat burr set. The advantage is that the flat burrs have a much longer grinding surface, since they do not need to take up real estate for bean crushing.
In general, I believe the longer the coarse grinding section on a burr set, the better the grind. Even well mounted home grinders, like the Innova/Pavoni/Lux set work as well as small commercial flat burrs, since they have the same length grinding surface. True commercial conicals have the longest surfaces of all (the current Cimbali Max is a true burr grinder as far as I know).
Greg Scace had the same results comparing the Kony to the Cimbali Junior as I did in the M3 versus Mini comparison.
My experience with the M3 does not lead me to recommend it for anyone except people who cup coffee on a weekly basis, where the configuration comes into its own. The belt drive and burr mounts need to be tweaked every two weeks, and its usability for PFs is horrible. If I hadn't got addicted to the taste, I'd be back to the Mini in a flash. So the low cost of the Macap is very tempting, even to me.
There is one design problem with conical burrs housed in a conventional espresso grinder: the grinds exit. Since the rotation speed of these grinders is 400 to 600 RPM, rather than 1200 to 1800, the vanes that sweep the ground coffee out of the grind chamber into the doser move at 1/3 their intended speed. Therefore, grind clog-ups are a common issue to all the conical models. If you go for this or any other conical, get yourself a curved stick tool that can sweep out the chute whenever you grind, and check that the chute is easily accessible in the model you buy.