nothing wrong with it's alchemy type, it uses tectonic energy, while eastern uses nature energy, the thing that was wrong with fathers alchemy was his purpose of using it, nothing else, the reason why they see eastern as a little bit better is because it can be channeled at long ranges and is mainly developed for healing purposes, unlike amestrians wich was developed mainly as means to war.
Ed can't use alchemy anymore, he sacrificed it to get Al's body and soul back, he gave a toll of his total alchemical experience and abilities, in the last ep when Ed wanted to try using alchemy was to show how much alchemists are used to rely on it instead of good hard work to harden you body.
their journey most likely has something to do with simply exploring how alchemy is developing in other countries, the yalready know how amestrians alchemy developed, and Xing's as well, the huge difference makes up for a lot of research, if all goes well they could make an incredible book of knowledge, who knows, maybe in the future someone wil lstart a real academy of Alchemy, and thus is the reason how the Al-Revis Academy was created /jk
but it could be very interesting to get to know more ways and styles of alchemy.
