Since people were cool enough to respond to my "Seths v. Prophets" thread, I thought I'd report back. I went with the Prophets because (a) I liked what I had read about them; (b) they are a little stiffer than the Seths; and (c) I just had a good feeling about them.
I love my Prophets. I've only put two days on my prophets (today and yesterday), but they've served me very well.
Powder: Fucking perfect. Both today and yesterday I got several long, knee-high to waist-high powder runs here at Alyeska, which, by the way, got 283 inches of snow in, and my prophet were incredible. With my old mid-fats, I was always stuck in second gear when I got into the trees. But with my Prophets I could absolutely charge with confidence through the tightest of trees and hole shots.
Steeps: I did a few runs down Aly's Christmas Chute, which is about a 45-50 degree narrow chute that runs about 1500 feet before opening up. I had total control with the Prophs. The stiff tail does an excellent job of dumping excess speed. Also, the skis' light weight makes it easy to throw them around or do Scott Schmidt-style jump turns when needed. I didn't do any big-cliff drops, but the skis felt fine on a couple 6-10 foot drops.
Crud: Fine. I tend to do big GS turns pretty fast, and the Prophets were pretty stable under foot.
Bumps and Groomers: I didn't spend much time on either, but the Prophets seem fine when I did. At 100mm in the middle, they aren't super quick from edge to edge. But they have a good sidecut (33.5) and are fairly stiff for wide twins. Bumps are very doable and even fun. As for groomers, these skis aren't going to deliver a lot of pop of a turn like other skis, but they are decent for big GS turns and stable at high speeds.
Park: I didn't spend much time at Aly's diminutative park. I did one lap and the skis felt fine doing a 3 and a 5. They're okay switch but not great. I don't plan on taking them on any rails.
Size: I got the 186s. I'm 6'1", 190 lbs and ski fairly aggresively. The 186s were easy to move around yet stable at high speeds. Indeed, I'm not sure why they don't make a larger size, say 192s. I'd recommend people to go bigger with these skis.
Caveat: My old big-mountain skis were six-year-old mid fats. This was my first time on fat skis. I have no basis of comparison with similar skis like Seths and Gotamas, though I've almost nothing but good things about them.