Cutting the cheese is a great move. I know this goes against the beliefs of many, but please rein in Jazz a bit. The goofiness of it really, really set my teeth on edge. I'm cool with him being kind of rebellious, but it was so over the top. Just felt really awkward.
But for the love of god, don't start slapping the '86 soundtrack all over the movie. It just, doesn't, fit. The cartoon movie is a product of the 80s, so the 80s music is fine. But trying to turn the live-action movie into anything resembling a modern-day version of the cartoon series or film just seems like a bad idea. A mixture of parts that just shouldn't go together.
I wouldn't be totally averse to fiddling around with Megatron's voice, as it felt kinda odd to me. But a lot of the characters were voiced by the original actors, with a couple exceptions due to death and disagreements. But don't go overboard. Fix the movie, don't try and turn it into a cartoon.
But those're just my thoughts. I'm just a heathen Transformers cartoon hater.