You might want to take a look at the Goodhope convertible bag. It has features similar to the WF, but with some differences.
-It's lighter
-One main compartment, instead of two
-No slot for the handle of a wheelie bag
-It's $30 (includes s&h)
-It's primarily suited to carry-on
-Smaller by 0.5 in
I'm thinking about getting this to practice lightweight one bagging. The quality of the backpack straps isn't as good as the WF. Since I'm not climbing Annapurna, it should suffice.