In addition to the mega frequencies the new units have chirp 2D, DI, and SI. They also have the dedicated DI element in the transducer that makes for a LOT better DI image.
I believe those who think these images are doctored to make them look better just haven't been seeing enough of the images that regular folks like alphahawk have posted. Multiple forums I follow have regular folks posting some tremendous images....With the solix and the Helix series .... especially the Helix 12. A guy I talk to that runs all brands as part of his business says that the Helix 12 he has is absolutely awesome and that the images posted are actually not as good as seen on the unit since the .jpg picture file looses some of the detail.
I don't currently have a mega unit, but when I get ready to buy there is not doubt in my mind that it will be one of them.