very good stuff! use after nixwax rug wash! however, if your rug has ever in its life been washed with biological powder/liquid it wont ever take up the reproofer!
I'm a big fan of their products and use them regularly on my coats, boots, dog coats etc.
I've used then for the past to proof/reproof cheap rugs and been very successful, although I'd still probably have a good rug done professionally. Be aware the "wash in" stuff is quite hard on your washing machine and while you can do it in a tub, it takes AGES for the rug to dry. I've not found the spray as effective as it doesn't get into the seams and stitching, but worth a shot in the short term.
Haven't used it for washing/re-proofing rugs - but can vouch for it on jackets and gilets LOL! Wish I could find somewhere to buy larger quantity than my local saddler sells?