Wish I even had a gut feel that I could share, Koko. But it's been quite awhile since I used KA. And I don't really watch the clock during a rise. I just periodically check the dough, and when it's ready, it's ready.
If I were forced to state an opinion, I'd guess that with W I'm typically running 1 1/2-2 hours on the first rise. That would be using a preferment and additional yeast ranging from zero to one teaspoon. The exception: Kastel's recipe for soft pretzels, which uses a pate fermentee and 2 1/2 teaspoons of additional instant yeast, then goes directly to shaping.
I'm thinking you're probably right about hydration. With KA I almost always used the full amount of water called for, and more when the humidity was particularly low. If I do that with W I have to add an inordinate amount of additional flour to get a proper dough.
The Weisenburger seems to need an early autolyse to prevent over hydration. That is, when you first mix it it seems too dry. Then it's suddenly wet. If that makes sense. Usually I mix the ingredients until they just come together and separate from the inside of the mixing bowl. Then I let it rest, in the mixing bowl, for up to five minutes before making adjustments and kneading. Given the short amount of rest time I'm not sure if autolyse is the correct usage, but I'm sure you know what I mean.
Basically, what I'm saying is that the W seems slower to absorb the liquid, and needs time to do so.
As you know, though, so much of this is based on feel, that it's really hard to generalize.