One of the options in dealing with Krathanos is to negotiate with him, where he may offer to trade his belt for release from Last Resort. If the characters go through with this, would you give them XP as though they had defeated Krathanos in battle? They have overcome the challenge, after all, and successfully retrieved the belt. Or would you give them some other amount of XP, or none?
I'm pretty sure I gave my party full XP for negotiating.
Greg
I also gave my party full XP for negotiating. Krathanos didn't care where he ended as long as the party went with him (so they couldn't send him to a harmful place). My players plane shifted with him to Heaven, thinking that the angels would be able to deal with him.
In this situation it is better to talk than to fight, and a reward is appropriate. A titan in Pathfinder is a tough foe (mine was a thanatotic titan with tarry demondands as servants instead of gargoyles) so striking a deal could save the party from a painful death (wich they should have lots along the AP)