1) Best bag I've used in 10+ years of being a messenger.
2) I think it's plenty comfy just standing around posing, or carrying covert beers while spectating.

3) The way the suspended straps work. No bag (except the ones that copied the design) can carry a big load better than the PAC. I've got the X strap, but hardly use it. I carry up to 60+lbs without using it rather comfortably over short hauls. The front buckle is nice for getting in/out of the bag when heavily laden.
4) Sure, if you consider I've used it almost every weekday for five years now. I found the non-suspended inner layer does pull moisture into the bag on really rainy days. I removed the inner cordura layer which reduced the effect greatly, but has increased the rate of wear on the liner.

5) The outter part of the bag has held up fine over 5+ years. I have broke a few small buckles, but they are replaceable at the local hardware store. I have worn out two main straps, and am working on my third. I removed all the Velcro because it's pointless after 6 months of courier work. It doesn't hold the flap down in high winds anymore, and just snags up your walker wear.
6) The big plastic buckle has been fine. The male piece (which is most likely to be the half that breaks) would be simple stupid to replace if it broke.
Deluxe bag