Like many of you I have purchased several different packs, vests, etc.
Vest first, then a William Joseph chest pack. The chest pack started annoying the heck out of me unless it was almost empty, so then it was a lanyard and an ultra light Chicobag backpack. The latest combination will still be used on backpacking trips, however for day trips I believe the sling pack will serve me well.
Orvis is always sending me $25 off $50 coupons, and I recently picked up the sling pack using one of them. Though I haven't had it on the water yet, I really like how things attach and how the huge pocket can hold many fly boxes with ease. It does not feel "in the way" when loaded like the chest pack. I'm taking a trip to Virginia for some fishing on Thursday, and the sling pack will have its maiden voyage.