Ive used the Barbour wax with very good results, I keep a cloth specifically for application and use a paint stripper bot air gun to melt the wax into the fabric (Carefully as it get very hot, a hair drier would probably be better!) Ive done Coats, Gas mask bags, baseball hats, all turned out very successfully, some needing a couple of applications, all very waterproof.
I have also redone my Filson Levi jacket with the Filson product, works just as well, but I guess the Barbour is more freely available.....
I doubt you will be disappointed....
Paul