I skied these in a 177 a few weeks ago in firm, chalky conditions. I'm 5'9", ski 3-6 days a week at Alta, and this year have spent most of my time on 183Gotamas, though my quiver includes 160 SX9, 167 Phat Luv (for sale), 174 Phat Luv (AT setup), 178 Hippy Stinx (tele), 180 Big Stix 106, and I've spent a lot of time in the past on 178 G41s and G4s.
I REALLY wanted to like these, as I saw the Movement Black Rose (which is the women's version of the Thunder and is the only women's specific ski I've ever heard of that only comes in a 175 and 185 length). No one demos the Black Rose, but the Thunder is supposedly almost identical with just cosmetic differences.
So as far as the 177 Thunder goes, they ski softer than they felt flexing them. My main problem was that I felt the mounting point was too far forward. The sweet spot felt small, and was directly under my arch. If I pressured my toes or the boot tongues, they didn't ski well at all and refused to carve. The whole setup felt like I needed to swivel the skis rather than turn them, and as with any center mounted ski I've tried, I don't like it. (My husband LOVES center mounted skis - PRs, Seth Pistols, Line Motherships, and has his BROs mounted forward. Personally, I just don't like the way it feels compared to a traditional mount point. But if you like center mounted skis, you'd probably love these). Anyway, once I figured out to pressure just my arch, I could get them to carve nicely on the groomed. I'd probably like them a lot more if they were mounted farther back. I will say they are very stable while running flat, which combined with feeling relatively soft made them the easiest ski to handle on bumpy traverses that I've skied in a long time. They were pretty stable at speed, and once I figured out where the sweet spot was, they were pretty fun to ski. I tried to figure out the demo bindings to move them farther back, but I didn't see any obvious way to just slide the whole binding back and the shop I demoed them from was down in the valley. With my history of wrecked knees I didn't want to mess with bindings too much. (Which bums me out - it would have been a lot more fun to demo if I could have played around with the mounting point).
I also demoed the B3, B4, im88, Mojo 90 and Mantra. With the Thunder I thought I'd like them with the mounting point straightened out, but I LOVED the im88 and Mantra. (and FWIW, liked the B4, didn't like the B3, and really didn't like the Mojo 90). Ended up buying the im88 as I figured the Mantra overlaps a bit too much with my Gotamas.