I think that the poster above, group theory, is pretty much right on there. You must do well on the MCAT no matter where you go.
That being said, even though it has been said that CC courses are not as tough as University courses... I think, in my opinion as well as many others, that the opposite may be true.
For example, at your standard university the prof is usually there to work on research primarily, teaching is usually a secondary requirement, and maybe even an annoyance to the prof, which often leads to less interest in helping students learn. However, at a CC the instructors are primarlily there to teach period. It doesn't seem a stretch to see the advantage already in CC, especially when you consider that the "expert" ie, the professor, at a university usually only gives the big lecture for about 100+ students, in a huge lecture hall. Then, the hands on, practical labs are taught by TA's. Often times it is difficult for TA's and Profs to communicate to help a student who is in need of help simply due to the volume of students and the lack of constant supervision from the prof. While at a CC the instructor, also the "expert," is in charge of labs and lecture of which approx only 25-30 student s total, usually. This gives much more attention to the student's and allows them to meet the needs in meeting education for that subject. Furthermore, the instructor (either MS or PhD) is there because they love to teach.
Of course the scope of the curriculum and concepts of the subject matter must be comparable to that of the Universities, in order for this argument to be valid. In which case you should compare the curriculum to be covered to that of the national standard that is covered for that particular science subject. For example, I took Orgo at a CC, I checked how the curriculum compared to the local state U. They covered the same volume of information and concepts, even used the same text! Last, my CC instructor also had us take the national orgo stadardized test at the end of second semester for the final, just to see and prove how well we'd do compared to the entire nation of orgo programs. We did about 83% average.
One more point has to do with gradeing/testing at CC vs University. When a larger University has so many students in a class it is difficult to give any more detailed tests than multiply choice, simply because of the ease of grading. While at the CC, they have less students and if the prof/insructor is ambitious, they give much tougher detailed, concept based tests that require you to supply the answers...finish a reaction drawing, do a synthesis problem, multiple step drawing... these things really require much more detailed conceptual knowlege to test well, when compared to multiple choice tests, like most large classes at University. Well, at least I think that multiple choice tests are a little easier than fill in the blank.
Anyhow, just something to think about. Good luck with your plan, it could work fine if you buckle down. CC, though often looked down on, are sometimes actually better at educating you in a given subject than the university. To bad that people don't always recognize that. It' s kinda also the way it is with Ivy schools so much tougher than lesser prestigious universities...are they really? I don't know, probably not near so as people think.