That's a better setup than what I was thinking of. The only problem I can think of is that the geometry of the pulling line would be tricky. I think you would have to keep it a little off from vertical to keep it from rubbing on anything. Maybe you could use a rigid puller with a crook in it to avoid that (sort of like an upside down "L").

A couple of observations:

The 58mm plain block had slightly more friction than the 47mm ball bearing block for the same line diameter. The gap also widened at higher loads.

Figure 4 would probably tell a different story if you used the 415N load level rather than the 174 N. I expect the ball bearing block would look better. (for US readers, 415N is 93 lbf, 174N is 39 lbf)

It would be really nice if you could compare a ball bearing block to a plain bearing block of the same sheave diameter. Actually it would nice to see that comparison at several different sheave diameters. Also, it would be nice to see a comparison of a new ball bearing block to a used one.

/ Just a Civil Engineer who sometimes plays with dirt in the lab.