i say go for the 2800+ barton, if u have the money, the extra cache will give u a preformance boost, also u can have fun o/c'ing it and hardly anyone knows the limit at the moment....
however i have seen some1 on a different forum getting 3.1ghz with a 2800+ barton, but thats ofcourse with prometai, and mad vcore which i cant remember, gl and hf!