I've previously owned a Giant Roam, which is basically the same thing as a Trek Dual Sport. I also own an older Trek MultiTrack (which is similar to a modern FX) and I also own a hard tail MTB (similar to a Marlin). I'd probably recommend the Marlin for most general on/off road use. It doesn't really give up a lot to the Dual Sport, especially if you fit it with tires optimized for how you ride. And you only gain capability for more dirt-oriented riding if you do get into that. I think you'll like the longer travel fork on the Marlin (the DS's 63mm fork's usefulness is somewhat limited). The Marlin has the same types of rack mounts and bottle cage mounts that the DS has, so you can mount nearly anything you wish to it.