i have heard from friends at other med schools that it was difficult to remember all the basic science after being on the wards. sure you see diseases that are covered in FA, but you probably wont see alot of the obscure ones that are highly tested (ie pheochromocytoma, marfan's, etc).
i thought about taking step 1 after my medicine rotation b/c i thought that it would help with pharm too, but after talking with a few upper classmen, i got convinced that after 2nd year was the best time to do so. they said that the pharm used on the wards doesnt help u in the manner that's it's tested on the boards--ie SEs, mechanisms, etc. that stuff is more just memorization and understanding FA.