I will say that I absolutely LOVE my Grip A14. I've had it for over two years and I don't know how many rounds, at least a couple hundred if not more and it's pretty much as good as new aside from the usual grime and what not. Plastic rails on the bottom are fine and not broken at all, no frayed stitching or anything coming loose. The only real giveaway that it isn't new is the top tends to sag to the left or right since the sides have broken in.
Having said that, at the price point and had I not been able to buy the Grip bag in the store at that instant and have it for my round immediately after purchase, I may have ended up with one of the Spinal Taps, although IIRC they didn't have the warranty at the time that they do now (I bought the A14 in I think March or April of 2015). The ones I've seen in person seem to have the same quality as the Grip, and I think they use similar materials, so I think it really comes down to your price and what features of each bag you prefer. The Grip has loads of storage as is, and the new expandable pockets appear to hold even more. But the Spinal Tap has that awesome mini pocket and what have you. So really, I don't think you can go wrong either way, but I KNOW you won't regret buying a Grip if you purchase one.