Rapha, nice but a bit pricey?

has anyone used the new washing/reproofing stuff? my rain jacket (cream) is well overdue for a rinse.
I've used nikwax before for other stuff but I would prefer to have a dirty jacket than loose rain proofness

I got the Merino wash to try out and I strongly suspect it's re-branded Graingers as that's what I usually use.

(Graingers works out quite a bit cheaper.)