Cara, Graham is the manufacturer of CiloGear packs. He obviously knows what he is talking about.
I understand why Ripstop is stronger fabric then taffeta. But it may not mean it is more abrasion resistant.
This is what Roger Caffin has to say:
Ripstop weave is a variation on the plain weave which is suposed to be important for gear. In this design heavier threads are placed at regular intervals in both directions. This produces a grid pattern in the fabric. The idea is to make the fabric a bit stronger against tears: the heavier ripstop thread won't let the tear propagate. The idea is nice, and I must say the ripstop fabric is more interesting to look at compared to a plain weave. However, it may not be any better than a plain weave, and under many conditions it is actually worse. There are three reasons for saying this.
First, modern synthetics don't tear very easily, You have to be pretty violent to damage them, and then the ripstop thread is not much use anyhow. The addition of the ripstop thread adds no strength in practice.
Second, the ripstop thread sticks up from the surface of the fabric. When the fabric rubs up against something there is always the risk of damage, but with a plain weave the load is spread out and the fabric often slides safely. But the raised ripstop thread focuses the load onto the thicker ripstop thread and onto the other threads as they cross it - especially the other ripstop thread. You can get abrasion focused on these small areas where a plain fabric would have escaped without damage.
Finally, the larger ripstop threads distort the fine micro-structure of the weave, and this makes weak spots for any coating. Hold a light coated ripstop fabric up to a bright light and you will see points of light around the ripstop threads, especially where they cross. This is where the coating will fail first. I discovered this while pressure-testing many coated fabrics: they leaked first at the cross-overs.