Hello CD-4 and LP Fans,
I find it fascinating that these techno-rumors get started, become some sort of de-facto standard, and then promulgated. And now the techno-truth (sorry about the tongue and cheek).
The Shibata stylus was designed for one purpose and that was to reduce groove damage during playback. Originally it was thought that the 30KHz sub-carriers would wear faster than the lower frequency undulations. The reason was that a .7 mil conical or a .3 mil by .7mil elliptical stylus tracking at 1.5 grams exerts a tracking pressure of 15000 lbs. per square inch at the groove contact points. This point contact, after a number of plays on LPs and 45s, mono, stereo, or CD-4 will create a trough in the record groove at the contact point.
The Shibata stylus tracking at the same 1.5 grams exerts only 150 lbs. pressure on the groove at the line contact points. The line contact distributes the pressure over a larger groove area, thus significantly reducing record wear.
I would never play any of my record collection with any stylus other than a Shibata tipped one. One additional factor is that the Shibata tip will yield very satisfactory playback of damaged records because it will play the part of the groove that has not been touched by the point contact stylus.
With regards to stylus wear, you should already have figured out the answer. If the wear on the groove is reduced, the life of the stylus is increased. Actually, the Shibata tip will typically yield one order of magnitude greater life than any point contact stylus.
Scooping out emulsified dirt has no effect on stylus life.