So, I've changed the nylon bearing to the SME original steel one. What can I say...what a fantastic change in my circumstances (SPU Meister Silver)! More direct, cleaner and present sound. More resolving, "aggressive" groove reading. The upper mids and HF more refined, flowing, with a lot of inner structure exposed. Esp. on operatic alto its easier to discern the lyrics. The dynamical contrasts better exposed, following the work and idea of record engineers is easier. Definitely my cup of tea, this is what I was looking for! The other side of the medal is a bit less tolerance to record imperfections - surface noise and groove damage more exposed.
A tip to those considering this change - unscrew first the rear bearing screw. Then *before* unscrewing the front, carefully put a thin screwdriver or a toothpick inside the arm to hold the grounding connection in place. Then make the change with one hand, holding with the other the toothpick in place. Saves lots of time (from initial 1.5h to about 15mins in my case).
All in all a fantastically invested 200GBP, together with a change to medical grade tubes at the RIAA (which was more icing on the cake compared to the bearing).
Cheers,