I use both Eagle Creek and E-bags. Both are fine.

As previous poster pointed out, these are not really space savers, but they do help you organize. For a six month trip in one (or only a few spots), I don't think they will add a lot of value to your packing. I find them especially useful when I am on a multi-leg trip with relatively short stays so I can put the stuff I need all in one cube and I only have to pull that out of the bag.