I washed my 12 year old Gore-Tex EMS mountain parka in Nik Wax TX Direct Wash-In DWR. Later, forgetting I had done this to the parka I sprayed it with Revivex DWR.
Then I remembered I'd done the Nik Wax treatment. So I tested the parka under my sink faucet's spray nozzle and WOW! TOTAL DWR! Absolutely no wetting through after several minutes of hard spray on the same spot.
My seat-of-the-pants feeling is that using both DWRs was the key to this performance.
Oh, yeah, there was no breathability problem after using the Nik Wax wash in DWR on this and several other GTX garments including PacLite. I always washed the GTX garments with the Nik Wax wash liquid before treating with DWR.