This is my first running hydration pack, so I don't have a point of reference, except for a hiking pack from Camelbak. The E-Race is much more stable, and body-hugging. There is still a little bounce when the pack is full, but I don't think this can be avoided in any pack, no matter the design (there is too much inertia in 1.5-2 liters of water). The great thing is that the weight is distributed across the chest as well, and not just on the shoulders. This is a minimalist pack, with just a couple of hip pockets in which to store a cell phone and gu packets. The BOA system does work as advertised, keeping the fluid bladder compressed so it's easy to drink via the bite valve. Overall, I'm very satisfied with this pack.

I wear a 9.5US, but 9 was better in these. I've done 4 runs so far and they work very well. The lacing system is excellent, as I can leave the forefoot (which is snug to start with) relatively slack and only tighten the upper half around the ankle. Very stable for the uneven stuff. The ankle was rock solid. Cushioning is better than on minimalist shoes (like Inov8). Light, snug, cushioned well, grippy Vibram outsole. Two thumbs up. (150lbs, med arch, D)

Based on two runs so far (5-6 mi), on very rough, steep single track (rocks, branches, very irregular rain-altered, pine needle covered off camber with drop offs). The shoes work well on this type of rough, irregular terrain, and you actually feel the spikes taking the shock of the foot strike. This is especially noticeable on the descents, where the Trail Fly really shines. Even on an extremely steep 3 mile descent, without holding back, the shock was absorbed and my feet and ankles did not suffer any injury. Good support. Me: 5ft 8in, 150lbs, Size 9.5, D. The fit was too wide overall (esp forefoot). Using the low volume insole, my toes were pointed up. Low mark is for fit; performance was great.