My wife and I both have GG packs (Miniposa & Mariposa). We've had them for a bit over a year now, and have had great results. I finally removed the waste and sternum straps on mine, as they were just in the way for me (my wife still uses both). At 14.45oz, my modified Mariposa is actually larger than I need for most of my outings.
Since I am in the Vegas area, water can be scarce depending on your route. At about 25lbs, the pack is beginning to be uncomfortable, but with an 8lb base weight, it's great on most of my trips. I only push the higher weights on the trips that I need to carry allot of water, and it obviously gets better as the trip goes on. The trade-off is a less comfortable pack when it's heavy, but since it's lighter most of the time, the added comfort of less weight is well worth it. And the newer GG has removable waste straps, which would give you the option depending on your plans.