gambit - I agree with you on the choice of the heavier twill.
I have the 24 hour briefcase and I love it. The extra pockets on the front (compared to the Original briefcase, for example) just make it too damn convenient. I am always sliding in a water bottle, or my sunglass case in the slots behind the pocket and keep a small camera and other random stuff in the pockets.
BUT - the moment they come out with a similar bag with the heavier 22 oz twill, I'll probably buy it the day it comes out.
The lighter-weight cloth on the 24 hour bag is awesome, but just not quite as awesome as the 22 oz twill.
I really like the functionality of the 24 hour bag. If they came out with one in 22 oz twill AND made the the front pockets like an accordion style where the pockets are flat when empty and only extend out when thing are put in there (not sure what it's called), then I'd jump on that. I just don't want the pockets sticking out for no reason.
I have the lighter tin cloth on the Meridian duffle and love it. Not sure why Filson discontinued that model, but it's worked great for me.