In some gear you mentioned, I think it would be much better to use just waterproof fabrics, especially if it should be cheap.
My first concern is durability of the fabrics, for example in a pack. I don't have good experience with cheap WP/B fabrics (nylon with hydrophilic PU membrane, what is probably the only option that can be found cheap). For examples, trousers made of such a fabrics started to leak at knees almost immediately. On the other hand, a more expensive fabrics may work much better. I have made a pair of socks out of 2.5 layer goretex paclite and they still work fine after a year of occasional use. I can hardly imagine stressing the fabrics more than using it for socks.
Secondly, the WP/B fabrics doesn't work just in one direction. It simply transfer water from the side with higher potential to the other one. In clothing, it is usually warmer inside, and this gradient helps to transfer the moisture out. If you put dry gear in a WP/B backpack and subject it to wet conditions, the humidity gradient will slowly (very slowly) transport the water into your pack. I'd prefer just waterproof fabrics here.
To conclude, it would be much better to use appropriate material for each piece of gear, WP/B is not universal solution to everything.