Rim Protectors - Anyone have any experience?

[gronk]

Hi, getting paranoid about my 20in alloys. Because they are polished the only place I could get insurance cover was via the OPC who were quoting a prohibitive price.

I know somewhere local who can refurbish @ £100 a wheel so its not the end of the world but as prevention is better than a cure I was reminded about the 3rd party alloy rim protectors that I used to see advertised in the back of magazines and was wondering if anyone has any experience of these i.e.: are they any good? do they cause other problems etc? Any recommended types? Other options even?

All opinions welcome