Jeff,
I would expect any vendor to prefer the products he happens to sell. In this case, both Tormek and Vadim seem polite and professional. I do not believe either has an axe to grind with the other. Tormek is experiencing rapid growth due in part to heightened interest in knife sharpening due to Vadim's research. Tormeks are the workhorses in Vadim's sharpening business. This seems like a win-win situation to me.
Out of respect for Tormek, Vadim stopped posting about CBN wheels when he began selling his own CBN wheels. This avoidance of a possible conflict of interest is honorable.
The hardness difference between diamond and CBN is a well documented fact.
Youngbin,
You ask a very valid question. When I first reviewed CBN wheels for the forum, the Tormek diamond wheels were not yet in existance. The only one I was aware of who used them on a Tormek was Vadim. At the time, I had already been looking for a coarse grinding wheel for my Tormek. I had already found the Norton 3X 46 and 80 grit wheels. They both cut quickly and can be used wet with the Tormek with water. I should say that they can be adapted to work with the Tormek. The largest diameter available is eight inches (200mm). This is perfect for the T4 but constraining for the T8. They have a one inch bore, requiring an adaptor to for the 12mm Tormek shaft. (This is not a big project.) They have both the pros and cons of conventional grinding wheels like the SG series: They diminish in diameter with use. They need occasional retruing. They can be retrued and dressed, so this is both a curse and a blessing. Like the SG, they can be used with heavy grinding pressure. If they were ever made to Tormek specifications, they would be my first choice for heavy grinding.
When Tormek introduced the 250mm diamond wheels, there were no CBN wheels ideally suited for wet Tormek sharpening. The CBN wheels at the time were ideally suited for high speed, eight inch dry grinders.
Granted, CBN wheels grind cooler than conventional wheels, however, they still have dust problems when used dry. So do the earlier Tormek 200mm diamond wheels. In fairness, Tormek has only marketed these for the T2, which is only used dry. There are rumors of a new series of 200mm diamond wheels from Tormek which can be used wet or dry, like the 250mm series. The new CBN wheels, pioneered by Knife Grinders have accurately machined 12 mm bores and binding which is designed for wet grinding. Both diamond and CBN wheels require careful use to reach full longevity.
I believe the tried and true SG wheels will remain the practical choice for most Tormek users. However, the present generation of both diamond and CBN wheels have become much better suited for the Tormek environment. I have used both. Both get the job done.
Ken
