Re cement cleaner on s/s this sounds an interesting solution but I'm not sure about the long term affects on the rubber bush, but I see that Brian has a Bravo 1 leg so may have the flo torque system so would be able to remove all the bush from the prop before treating it this way. Be very wary of using this system on aluminium props as I think cement cleaner is caustic based, but I'm not sure.
Once cleaned I would advise that you do cover the with some sort of spay to protect it as some brands of propeller are more prone to corrosion, especially inside the hub, you can spray with "corrosion guard" which is supplied by Mercury for protecting propellers, although there are loads of other products on the market which leave a film over the surface.
A polished prop certainly looks nice but it will not work any better, damage is the killer of performance, however minimal it may seem, so the prop should be checked for any signs of damage to keep it in tip top condition
propeller repairs & sales