In reply to Tony the Blade: Its a good craic, always hard work but also always a good atmosphere. I've entered the Med Score with my old man this year. Last year the missus and I did the B (she didn't talk to me all the way home...). The two years previously I did the B class and Med Score respectively.
I'm not very competitive about it, but its nice to push yourself and see how you get on. Some amazing times and efforts put in by a lot of teams though.
The format has always been pitch up Fri night and register, tent city Fri night, start running in the morning, make it to the overnight camp by early evening, mong it for about 14 hours, then run/hobble over the back half of the course to the finish, whereby you have a free scoff courtesy of 'Fat Wilf'. Happy days!
The entry booklet thing tells you everything you need to know about kit and the website has bits about training and toptips. I'd say sack comfort off as much as possible, but be careful about not taking enough in terms of layers. I've always been very lucky with the weather, but the first day of the Brecons (my first KIMM) was minging, and the first day of last year was pretty bad too. Running wet and cold can be done as long as you're fit and don't get injured. But it doesn't take much, and you're suddenly in clip!