they are about the same volume (Newt to Ion in size L). I am happy to have both as they are both sweet packs. Newt does have more padded shoulder straps to Ion and different closure system (zip closure on Ion vs. snap and roll top closure on my version of Newt). They are both made from dyneema so comparable in durability and about the same weight. To me both are clean looking packs and bungee on Newt's front does add a bit more versatility to it.Have been using both for some time now and there's no wear or tear on them. At first i did find closure system on Newt more fiddly to Ion's simple zip closure but once you get used to it it's realy easy. As I can see on new Newt the closure system has been changed to drybag closure system so should be easy to close and open. There's no hipbelt on Newt but with light loads they are made for you will not miss one:).