I own a Summicron 50mm lens which currently needs a cleaning job. However, I'm so worried about losing the coating of the lens by the cleaning process in order to get rid of the fog.

I've been told by the person at the repair shop that my lens, which is old enough will likely lose the coating a bit in the cleaning process since the coating has already been slowing decaying, and there's nothing I can do about it.

Since it's not a cheap lens, I need to have a little sanity check here: Is it normal and acceptable to take this as a choice? Or should I cancel the cleaning and stick to the lens in the corrent condition with the fog and just keep using it until the fog really starts to bother me and ruin the image quality?

What are your experiences on making your decisions for the lens cleaning when there's obviously going to be some loss?