This is my third Synergy over the past 8 years. The first one I bought used to have the sternum strap, which I liked as it balanced and kept the backpack tight on my shoulders. This gadget was gone after I bought the second one. This last I bought, I noticed that most of the pockets (cell phone, light, pens) which used to have a strap on elastic band, they lost it on this version and this also was slightly disappointing.
In terms of durability, I make an extensive use of it with my job loading it often with some 20 lb. Usually after 3 years the bottom starts chipping and it may lose few sewing stitches.
It organizes all my tools very well so I have everything handy, but it is not water proof, everything gets wet inside with rain.
Overall I am happy as I have not found another model with all these accessories in this price range.