Barton don't recommend using bearing blocks if the keel will be left in the raised position as the balls deform under static load. I did fit bearing blocks when the boat was kept on its trailer, and there was a noticeable difference. Since I had a No3 block deform, and the rope jammed between the cheek and the sheave, I have changed to size 4 plain blocks, and replaced the deck block (still size 3 but now running true on its shaft) and it has become almost simple to raise. It is easier With someone tailing the uphaul, but not difficult to do it solo.I think increasing the sheave diameter and having new sheave/shafts has made more difference than fitting rollers, but that is hardly a scientific comparison!
Loosening the bolt on which the roller runs did it for me, but I am not convinced it is large enough to protrude beyond the cheek blocks. It seems a bit of a mismatch of sizes for roller, bolt hole, and bolt, but there is no sign off any adverse effect.