Well, I am prejudiced against bump knurling tools. Mainly because I have used the scissor type now for about 25 years, so I see the advantages. I have a couple of bump style, but they never get used. Considering the pressure required to upset the metal in a knurl, the design of the scissor style logically must absorb the lion's share of it in the pivot pin and the axle pins of the rolls. In a bump style, the tool is simply brought to bear against the material until enough pressure is there to upset the material. All of that force is pretty much absorbed by the spindle and tailstock, if used, along with the axle pins of the rolls. Also, to knurl long pieces, a bump tool is out.
Granted, lathe bearings are, as a rule, robust, and take an enormous amount of pressure while taking heavy cuts, or during large drilling. I'll never say that the bearings will not tolerate the pressure from old fashioned knurling, but if there is a method that reduces that pressure, I'll use it.
Interestingly, several years ago I did a comparison between the two styles of tool on a small CNC, a Kia Seiki of some sort (about 20 hp), I forget the model. I was most interested in the electrical load. As I recall, using the scissor type tool dropped the motor load, as displayed in the current draw, by about 20%. That's not a measure of bearing stress, but I have to believe that if the motor load is down, so is the spindle stress, and hence bearing stress.
One note about adding paper under a toolpost. Use a couple of strips of 80 grit instead of plain paper.