It’s tempting to poke fun at Milemarker’s inability to keep itself intact for more than one recording and touring cycle. The band has featured more short-term members than a midget porn flick and endured more lineup changes than Saturday Night Live — its arena reunion tour would have more folks onstage than in the audience. But Milemarker’s continual evolution has led to interesting shifts in its musical direction. Milemarker began as an experimental Chapel Hill hobby, with the players trading instruments and toying with computer-manipulated sound snippets and multimedia concert props. Later, the group relocated to Chicago and moved toward straightforward rock before assuming its current ice-cold stance, which brims with interstellar ambience and the vaguely political outlook that has always informed its recordings. Milemarker’s winter romp traverses the left half of the country, downplaying its previous art-house theatrics in favor of short, sharp minimalism — a strategy that should piss someone off to the point of quitting by tour’s end.