I have reservations about multi-teeth as well. What happens when you dull or break 1 of the three teeth? Guess you just chunk the 3 tooth assembly and put on another $20 assembly. Kind of pricey to me. I would rather replace a $3 finger tooth or in my case with greenteeth loosen the tooth and turn to a new cutting edge
There are actually 4 teeth. And you do need to change the wheel as well, which can make 1st time replacement a bit pricey. (although some other brands require wheel replacement as well)
I did switch to MultiTip on one grinder, and can say that so far have been mroe than satisfied with the results. If you dull a tooth, it can be sharpened. Multi-Tip will also take them back with a small refund towards a new tooth. But you are right, I think they are around $15 or $16 per tooth if you need to actually replace one.
I do like the fewer parts involved, and the time to remove or replace teeth is significantly reduced over the original teeth (or any solution that uses the original teeth setup)