The Brown Santa brougt me a
Wingnut Assault today. The pack is just what I hoped. The small, low profile design sits flat against the back and harldy is noticed while riding. I loaded it up with 50 oz. of water, a 29er tube, a multi-tool and a CO2 cartridge. There was a bit more room inside for a few other odds and ends.
This will be my pack of choice for the upcoming E12. The bladder looks like it can be easily and quickly refilled. The pack is small enough that side pockets on the jersey are still usable. The Assault has the same mesh straps, complete with flask pouch as the other Wingnut packs. The back of the pack is also mesh, which makes for lighter weight, and more air flow.
The Assault looks to be a superb lap and supported hundie race pack. I am looking forward to using it more over the next few weeks as I get everything dialed in for the 24th.

The Wingnut Assault in red

The bladder is easily refilled while still in the pack
On a side note, I also tried out these
Fuel Belt bottles today. They are 10 oz. bottles that fit easily in a jersey pocket. There are also 7 oz. versions available. These are perfect for carrying along some extra liquids, whle still keeping the frame bottle free. They also fit well in the wingpockets on the Hyper 2.5. Thanks to Dave from Driggs for tipping me off on the bottles.

Fuel Belt 10 oz. bottles