I haven't gone on a long trip yet, but I have used one of the bags (the 14x10) in my 5.11 Moab 10 for clothes for an overnight a few times. On the overnight I decided to not use it, I really missed the organization - that is, I missed being able to pull the bag with my clothes out so I could get to the other stuff in my bag easily, without having the clothes falling out everywhere. I have ordered the larger set for my upcoming 2-week trip.
As some have mentioned, when zipping the compression zipper, it is really easy to snag, and that makes for a difficult mess. The solution is to keep your finger including a knuckle on the inside of the zipper to keep the material clear of the zipper. Works every time that way.