Weatherproofing is about the same, although we went through apocalyptic hell in the Dariens with nary a problem. I never felt brave enough to try this with the Kilimanjaros. On the Kilimanjaro, they are. Liner quality is definitely superior on the Dariens. You can wear it about and look a lot less dorky than with the Kilimanjaro one.
Cold protection is great for both.
Ventilation on both jackets is good. The First Gear has a cool mesh liner, and a few places where you can open up mesh vents. However, they don't let in as much air as I'd like. Similarly, the Dariens just have huge zippers you can open to let in air. Delightful when you're moving, but you tend to balloon a bit, which must look somewhat ridiculous.