I Have the Simms Flyweight Access boots specifically for multi-day rafting and backcountry trips where weight is critical. The boots have very grippy, but rather delicate soles. I've also had to use Aquaseal SR (shoe repair) to touch up some wear points near the laces after just a few weeks use. The ankle support is also pretty light and soft, but this is expected given the lightweight construction. I wouldn't recommend these boots at full price, but I'm content having paid about 50% of retail.
I would lean towards the regular, less expensive flyweight boot with the black, more durable vibram soles if I had to pay retail for a lightweight boot.
I mostly use my Simms G3 boots for fishing and when weight is of no concern since they are pretty bulletproof and provide great ankle support. I can comfortably hike 3-5 miles in the G3 boots with a medium-weight pack.
I bought the Orvis Ultralight last spring. Lots and lots of miles on them including a handful of 2-3 mile hikes and a moose pack in them over the season and they were great. Vibram sole, couple ounces lighter than the Simms Flyweight, and essentially the same price. I only went with the Orvis because of how they fit my foot with my preferred waders.
Orvis has gone a bit off the political deep end and I would've preferred the Simms for that reasons since weight, durability, grip, and cost are all about the same. But I could not compromise on fit and comfort.