Now, on to the comparisons! One of the benefits of the advanced shapes is to increase the contact radius. In theory the worst shape (the spherical) contacts the vinyl wall at an infinitesimal dot. So the contact area is (in theory), ZERO. But, of course, vinyl deformates, so a practical contact area will be established, and it will have to be estimated for the spherical.
Seems Namiki did an estimation of the contact areas. It is on his patent, though. JICO reproduces them on its SAS literature:
Note that "Line contact" here is actually the Shibata. Note the "r" radius (the side radius. The smaller the better will the higher frequencies read.
Another comparison of contact surfaces plus dimension data, this time from Audio Technica. The numbers are different:
Here for example you can see why a line contact shape is beneficial: The best high frequency readout will be obtained with a 0.2mil side radius (or smaller!). The .2x.7mil elliptical delivers it, but the contact surface is smaller than the standard elliptical or conical. The advanced shapes can give you the same (or smaller) side radius (better ability to read high frequencies) with a bigger contact surface (less wear). And that's why they are good.
Note that the last row (L1/L2 or "F") tells you how "tall" is the side contact, the taller the better since it means big contact area but with small side radius. Also note that the van den Hul is included on the comparison, and according to Audio Technica, the MicroLine is better.
Also note something more interesting. The minor/major radius dimensions, and footprint for the AT's MicroLine, is exactly the same as Jico's (Namiki's) SAS stylus. I bet they are exactly the same stylus
Moreover, if you go to JICO online store, you won't find the SAS stylus being sold for the current Audio Technica cartridges
! I bet Namiki is making both AT ML and JICO SAS styli.
Another thing to point out: AT's estimate more contact area for all shapes. That means they are using a different estimation of vinyl deformation.
Now, a footprint comparison from the JICO SAS flyer. Note that the line contact is the Shibata, it can be inmediately identified by the "heart" shaped footprint: