same here... Kuro letting Sakura embark upon a dangerous mission in his stead is very OOC for me...
Not necesarily. Kuro has often, in the past, let Syoaran off on his own to do dangerous things. Like letting him fight Seishiro (sp?) on his own...and that was before he understood that it wasn't real and he was in a virtual world.
He also hasn't had a lot of direct contact with Sakura. Sure, he watches over her...but he's primarily been involved with Fai and Syoaran.
Also, he has Fai to think about. For us, this has played out over weeks. In their relative time, Fai's being hurt and dying anf then being saved is very fresh. He also promised to look after Fai and is responsible for his life. While that may or may not be permanent, depending on whether Fai gets his eye back, right now Fai NEEDS Kuro.
There is no way Kuro could really leave Fai right now. What if Fai woke up and needed blood right away? Or What if he woke up and Kuro wasn't there and he tried to run away...or even kill himself? His mental stability following what has happened is likely to be shaky. No way Kuro would up and leave him to go on a quest right now.
So really, I think it is in character. But that's just me. *shrugs*