Yes, good call on the centre channel. This whole toeing-in thing is fraught with potential pitfalls - some speaker makers say "don't do it", others say "you must do it", yet others say "it depends..." and some give no advice at all. Personally, I can’t see how it can ever cause any problems *unless* the manufacturer has specifically designed the speaker in such a way that listening on-axis is wrong, which I can't understand either. Why design a speaker that way? MK and M&K give very specific advice about toeing-in, so it's easy for me (and you) to know what to do - and as a result my front LCR are all aimed very tightly at the MLP. It's an easy thing to experiment with though, so everyone ought to be able to get their speakers set up for the best way they can in their own rooms.
Another cause of post-Audyssey harshness or excessive brightness is not orienting the mic towards the ceiling when measuring, but all that is well covered in the FAQ.
I also like OldMovieNut's recent contribution and suggestion too.