I haven't taken my DAT yet but I have taken the MCAT. I don't know if your RC score will improve but the MCAT is definitely all about inferring things from the passage which is what everyone is saying the DAT RC is migrating towards (i.e. what is the author's tone? the author would probably support...). The bad part is the MCAT is structured way differently. The passages are about anything and everything, not just science stuff like the DAT. Also the passages are shorter and there are way more of them. The difficulty is that they hammer passage after passage at you and you have to try to stay focused and finish in time.