Andrew
I have dealt with all the companies you mention, as for buttons coming off I really think that is a universal problem, all these companies get their stock from the same supplier, I always reinforce my buttons when I buy a jacket.

I bought my 16oz Strome weight Isle of Skye from the Scottish Company, I would heartily recommend them, I lost some weight after measuring, I went into the shop one day wearing the kilt the immediately recognized the problem and fixed it right away. I've also had good experiences with Caringorm on numerous pieces to me they are wonderful people.

As for Burnett's and Struth I own a kilt from them and it is just perfect, remember Burnett's have been around for quite some time and have been the premier kilt maker for Police and military bands in Canada for some time, they are very knowledgeable and friendly. I went to them with my Aunt to have a tartan jacket made in my late Uncles tartan, we went up for the first fitting and it was perfect. There are going to be problems from any vendor. I'd say go with the shop that you are comfortable with. You may also want to check out the Wee Tartan Shop in Port Perry Ont.