I managed to miss this thread first time around, but a few observations: one is that it's not a clear-cut 'light is good, heavier is bad', with lightweight kit there's well-designed stuff that does the job and poorly made stuff that doesn't, same as with any other kit. Lightness is just one factor. Also, to complicate things further, as Mike Parsons is fond of pointing out, the lighter and more minimalist your kit, the more it makes demands on the skills of the user to optimise its effectiveness.
That could mean anything from packing a minimal sac so that the weight distribution is right and comfort is maximised through to simply knowing how to use a sleeping bag efficiently. Or even just knowing what to take and what you can leave out and what the implications for your personal comfort and safety are.
As far as durability goes, I think it's fair to say that lighter kit tends to be less durable than weightier stuff, though not always and it depends on the item. Lightweight boots, for example, tend to have thinner sole units and use EVA padding that compresses and deteriorates in use. With the right choice of fabrics, light clothing and equipment can be very tough. Chances are though that they'll also be expensive because high spec materials are more expensive.
With Golite, their initial range was aggressively minimalist, since then they've moved towards a slightly less spartan approach with both clothing and equipment and their latest packs ime are a good compromise between lightness, useability and toughness.
