Hmm...I think that Shinichi doesn't completely detest his form as Conan. There are the occasional perks during cases. I think what really gets to him is the helplessness of being a child and being unable to tell Ran anything. People take their identity for granted sometimes, so it's natural that he would hate "Conan" at first. I think that after a while, Shinichi got used to it and began to look on the slightly more optimistic side of everything. When the time comes, I'm sure that Shinichi will hesitate on whether or not he wants to turn back, but decide to do so anyways.