The vest itself is surprisingly heavy (compared to my MH 6-liter hydration pack at 5 oz) and is going to be warm on a hot day. Once the many adjustment points are dialed in, the pack carries a 7- to 8-pound load without bouncing or swaying while running at a 5 to 6 mi/hr pace. Sizing was tricky for me. At 5'7" and 142 lbs, I found that the M/L was too large even with the pack full and everything cinched down to the limit. Conversely, the S/M was small and barely fits with the sternum straps extended to their limit with only a tech shirt underneath. Note that the claimed weight of 15.5 oz is for the S/M. By my scale, the M/L is 3 oz heavier. Also, the pack capacity for the S/M is noticeably less for the S/M than the M/L. I do not know whether the claimed 11-liter capacity applies to the S/M or the M/L.
I have only gotten a few short runs in with it, but I think that I am going to like it a lot. Version 2 is now at a good price point with the introduction of Version 3. If you are looking for a running vest for those all day treks that rides comfortably and costs less than $100, this might be your best (only) option.
This review was written in the old system and had content requirements that are different than reviews written today.