Yep the cylinder head gasket is problematic on many 800's, but its not a major worry, just keep an eye on your oil level, nothing more to it, until you get the chance to replace it. Its quite big job, but not too hard.
Dreaming of Dakar
Everyone has a max speed, 90% of that max speed is much safer and easier, and if that 90% speed isn't fast enough at Dakar, you enter the snowball. - neduro