Thank you gazbot,

The tartan is Mackenzie modern, and it's 13oz. I bought it over twenty years ago and there is no damage from sporrans.

I'm going to be controversial here and suggest that in fact a chain does less damage than a strap, but only if is is completely smooth. I think the problem is that many modern chains are not as well made as they should be and it only takes one tiny rough piece of metal on a chain to quickly ruin a kilt. A leather strap on the other hand is pretty much guaranteed to do little or no damage.

I have been caught out in the rain on occasion (it is Scotland after all) and just wear a waterproof jacket, and gaiters on my legs. I have never had my kilt get wet all the way through, it seems that it would take a lot of rain to get more than the top layer of wool wet. I don't however wear the kilt if I know it's going to be a very wet day. An Inverness cape wouldn't really be practical for the sort of walking that I do.