I think this is a really interesting question. Trails Collective did a countdown of the toughest ultras and I thought that was super intriguing as well. From my perspective a rail trail or canal path ultra is more like a road marathon than a trail race and I wouldn’t include those. I think of trail running as a discipline that requires a big variety of skill sets that can offset each other over the distance and the super pancake flat stuff just isn’t part of the same category. From my limited experience I tend to agree with the races at Blue Marsh in PA (Blue Cruise, Naked Nick, Naked Bavarian, Naked Prussian) being great, fast, beginners trail ultras. I think most of the races average 100-150 feet per mile in gain and would give a newcomer a light trail experience. I think a beginner trail runner going from a canal path race to Laurel Highlands or Worlds End or Virgil Crest would have a pretty rude awakening!!! I think the other side of “fast” is the competition side and I think that’s really the more interesting part of the question. Trail Runner of the Year voting just happened and I listened to a podcast just discussing that. With regard to the mountain ultra trail races that get any respect nationally its all on the west coast with the obvious exception of JFK. I know we have great runners out east here too! With so many races out there though, and many of them filling up super fast its hard to know where the most competitive races are… So maybe I’m getting outside the topic but what are the most competitive races in the Northeast?