I actually think that the April test was HARDER to score well on.
here is my story: I studied for and took the April MCAT while taking biochem, genetics, genetics lab, and a psychopharmacology class. I studied on my own, did not take a prep course, but did take a bunch of practice tests (AAMC, a few Kaplan, a PR test), and felt confident that I could get a good score based on my performance on the practice tests.
I sat for the April test, and thought it went really well, except that I hadn't completely finished the verbal section. I had a really easy bio test, in particular, the easiest I had seen amongst any of the practice tests I'd ever taken. I got my scores back two months later and was sorely disappointed. I do not think my score was directly affected by the fact that I was taking four courses at the time, I think it was a result of the fact that the April test was easier and therefore harder to do really well on.
So, I decided to retake the test in August, even though i knew it would push me back in the cycle. I don't regret retaking it, although I REALLY hated having to wait for schools to get my new scores. I had the summer to study (while working 40 hours/week in lab), but really didn't do anything that differently, and I didn't study that much more during the summer than I had during the school year. Just went back over some things I felt shaky on, plus I tried to read more for pleasure to help me out on verbal.
Well, the night before the August test was horrible. I went to bed late, couldn't fall asleep until 1:30, and then woke up THREE times during the night. I felt crappy going into the test, which was only made worse by the fact that I was sitting next to a SNIFFER!!!! Who SNIFFED through the ENTIRE TEST. I felt HORRIBLE throughout the whole thing, and didn't even want to release my scores at the end. But I did, because I knew I had to if I planned to apply this year.
So, my scores finally came, and I ended up doing much, MUCH better on the August test (an increase of 5 points and two writing sample scores). This is what led me to say that the April test was harder to score well on. I felt better prepared for the April test, but I did not do as well as I had expected.
If I were you, I would still try to take the April test. That way, if you don't do well on it, you can take the August test and still apply. When I decided to study for the MCAT while taking classes, I did so while keeping in mind that when I get to med school, it's going to get a whole lot worse. So, why not practice now?
I am not sure if that helps you terribly, but I hope it does. Best of luck to you!!