Smitty, I own sitka gear (not their rain gear) and wear it for most light drizzles. If I am moving quite a bit, it works fine. Once I stop or slow down, I wear my HH Impertech. I have not worn all the various rain gear out there by any means, but through my experience, Gore-Tex generally leaks up here. I hear mixed reviews (some love it, others hate it) on the newest sitka gear, but it is also big time dollars, and I haven't yet made that jump. I have also not tried the newest Cabelas wear either.
You got some good advice in the general forum, but the best advice I would give you, is to go with what your guide recommends. He has seen most of the "newest" gear hunters bring up and can tell you what works and what doesn't. Whatever he uses will generally be the stuff that really works.
I would also recommend you go to
www.outdoorsdirectory.com and go to the forums there. This is a dedicated forum to Alaska hunting, fishing, and the gear it takes to handle our state. Do a search or post your questions. In regards to your rain gear, I would guess HH Impertech, Sitka Gear, and maybe a small smattering of Arcterryx or Mountain Hardwear will be your answers.
Please let us know what you decide on and then how your hunt goes. I imagine that you are getting more excited with each passing day.
Take care,
Garion