Toying with the idea of stepping it up to an ultra sooner rather than later (Keswick 50km in May). Wondering if any of you nutters who already do ultras could advise how the transition from marathons to ultras is, it looks as though a lot of the climbs are more of a walk, albeit with a fair old stride and the in-race nutrition is a lot more solid food than in road-based marathons. The longest I've done on a trail is half marathons, but I've found them more enjoyable to complete rather than aim for a time-based target (which is one of the main motivators for me on road races), and in some ways more enjoyable, the tougher they make the course.
I've got Seville marathon (flattest in Europe, just 10m altitude change over the whole course) in February, which will be marathon #7 for me and don't think I'll decide on Keswick until after this.
Any advice though would be great, cheers.
-Cove, Manchester is the same date as Yorkshire Half Marathon (Sheffield), which I'll be doing - cracking course which is pretty much all uphill for the first 5 miles.