Just wanted to pop back in here after a couple weeks in the Arc'teryx Vertex Speed Lows! The break-in period was a little rough - felt like a weird fit and achey, didn't feel so grippy, and the pressure was on because the Arc'teryx store in Boulder doesn't take returns and these bad boys are $190...but I'm super happy with the shoes now. Since I got them I've trail ran/hiked 50 miles (mostly around Boulder, with the longest single run around 10 mi), gotten probably around 25-30k vert, approached the Petit as well as soloing the first pitch, and done a fair amount of scrambling in the flatties (Freeway, Freeway downclimb, Stairway to Heaven, Baker's Way, DEF on the First).
The good:
After the initial break-in these are great scramblers, especially for slab. I felt very solid on DEF, especially on the first pitch - probably more so than in my old TX2s (which were tbf quite old). No sketchy moments or slips or anything. I'm not planning on making a habit of soloing anything harder than DEF in trail runners so very happy with that!
They are much more comfy to run in than approach shoes for damn sure.
The mid:
Definitely less comfy to run in than Prodigios or something. Not very cushy if you're primarily a trail runner doing phat miles on a regular basis, but that's not what I bought them for, and this is a rock climbing site.
The bad:
Not very good at edging. Pretty obvious as it's a hybrid running shoe but there were several edging moves on the first pitch of the Petit, and the soft sole that allows the Vertex to run also prevent it from confidently edging. That being said, it did fine, just not exactly a winner here compared to a classic approach shoe. If I was fully rock climbing or leading approach pitches or something, I'd just take TX2s.
The price. $190 is...not cheap. And while these are getting the job done, I can't say if they're $30-50 better than Bushidos or Mutants or any of the other classic running scramblers. They also seem durable enough but time will tell on that.
Overall though the shoe seems perfect for what I bought it for, which is trail running around Boulder with a good mix of scrambling in the Flatirons, and chunky alpine 5.easy. They don't run as well as a running shoe, and they don't climb as well as an approach shoe, but they do both well enough.