The struggle continues...
Bags I've run:
SPG Powder Pak: The thing is a sponge. None of the stitching is water proof. After a day of riding you can literally turn in upside down and wring the water out of it. Only one big pocket and no outside place for anything.
Burandt Bag: (Pro Chassis) What a piece of crap. If it didn't fall off the sled from the fasteners releasing themselves, it would flop around and damage stuff. Had to use bungee cords to keep the thing on the sled. Not even close to waterproof.
Holeshot QR Tunnel Bag: Meh. Didn't last very long. Fabric got frayed quickly. Tools in the pockets put holes in the bag. The stretchy mounting straps mean it's always moving/bouncing around. Not waterproof at all.
Giant Loop Revelstoke Bag: This has been my bag for the last two seasons. Actually, I've had two as I put a very small hole in the first one at some point last season. It is what it is: A heavy duty dry bag that has straps for tying it down. I try not to go into my tunnel bag much, so I really just want a place for my extra dry layers and goggles to stay dry and this does the job. Getting in and out of the bag during the day isn't the easiest/quickest operation. I organize my gear into smaller bags inside. It's light and simple with no zippers to fail. The strap loops the bag comes with suck to deal with when the straps are frozen and your hands are cold, however the Giant Loop 'Footmans Loop Anchor Kit' is easily adapted to the track on the Polaris and works really well. I just ran the straps through the loops and cinched them down. Never lost the bag. It's nice that the bag changes size to accommodate different size loads. There are external loops for tying gear to the outside of the bag.
The wife has been through all the same bags with the same luck. She hates the roll top Giant Loop bag as she gets in and out of her tunnel bag a lot more than I do. Last year she ran the large Mtn. Addiction bag and really liked that. However, she did have one zipper failure that they repaired at no charge.
For this season I think I'm going the Pelican case route. They're tough, waterproof, easy to access, have no zippers to fail, have no fabric to puncture, have no buckles to freeze, have no straps to deal with, and they are cheap.