Camio, yes the Good Run Guide website uses a complicated formula to work out the 'flat equivalent' distance. It's not based on the fact that the distance going up/down a hill is slightly longer than the crow flies but on the fact that you dont regain what you lost going up hill when going down the same hill. How meaningful this is I let you decide but I find it quite useful.
With the talk of the flat York marathon, a question. How much more difficult is Snod compared to your average 'flat' marathon? I've only done one marathon and that was Snod so I wouldn't know. The guy on TV a few years ago said Snod was the hardest marathon in Europe????
John, my father in law took me round the route of the Betws/Snowdonia half over Xmas and I was amazed at how tough the climb to the lake just after the start was, we struggled in the car. Still if I can do Waunfawr I can do that???