A friend of mine from Madrid is keen to come over for the November one in Cheshire and if he does will no doubt end up dragging me along too. Also considering the summer one in Scotland for sh**s and giggles.
I always find the crawling obstacles or any which involve steep hill climbs the hardest as they knacker your whole body and not just your legs!
Having said that I recon the distance alone will be a challenge on the tough mudder as it's a good few miles farther than most other events of this type