ummm....i beg to differ, all those classes are pretty difficult if not very hard depending on where you take them.....you need to have time to practice taking the MCAT above anything else i believe....also, there is a lot of junk from orgo that you don't really need to know for the MCAT but you do need to know for your Orgo midterms and final (same goes with biochem, and maybe a little bit for human phys)....this is just my opinion though....
i suggest if you are really intent on taking the MCAT, but do not want to change your classes, do it (b/c no one should tell you what to do) BUT make sure you take real test situation practice MCATs and if you are satisfied come test time with the results, take the MCAT....if not, dont take it...