Mate, if you want to drive to Mudgee one weekend or meet in the mountains, you can borrow my Meade 10" ACF and see what you think, or just come up and have a look through it here.
I see no difference between the flatness of field between the Meade and the Celestron EDGEHD, there is definitely a difference between the and the standard SCTs though.
The celestrons have the advantage of Hyperstar if you are thinking of photography, and its okay Brendan, I'm not a fan of Newts or Dobs
You may want to check the weight of each OTA, the CGEM is only equivalent to the EQ6Pro in how much it can carry for photography, but any of them will be great on planetary and globular clusters.
The main issue with all of them is cooling, but I have found that easy enough to work around.
Really the differences between them are negligible optically they all perform as well as each other.