I like mine a bunch. I can't speak to the Sitka gear as I've never owned any but I did sell a Kuiu Chugach which my First Lite outshines by quite a bit.
There are a few reviews out there comparing them on Rokslide. Check out the rain gear shootout it talks about all of top end rain jackets. Was good reading and talks a bit about the technology and breathability and features. Just got my stormtight also but have been using the stormfront the last year and super impressed with the durability of the stormfront. Bought the FL Stormtight for a lighter rain jacket option. As far as quality and such I cant speak on yet or how dry it keeps me till I get out there with it. Overall first appearance and with the quality firstlite puts out I have no reservations or buyers remorse at all. Cant wait to test it this coming year.
I stopped using my FL a couple years ago. I found the waterproof main zipper wasn't necessary and was actually difficult to manipulate with one hand. I also had condensation problems on the interior. I switched to Kuiu and haven't looked back. I'm working on sewing in a new zipper into the FL and I'll just give it to a friend.