I have a mega 10 and a mega 12 g2n, to be honest I think you would be splitting (hairs) as they say in regards to picture quality being any better than these units. This is just my opinion but It gets to a point where you are wasting your money for details so minuet you really cant benefit from them.
These Helix mega units are more than any fisherman would ever need, UNLESS money is no problem? Then I would up date every two yrs just for bragging rights!
Find a Helix 12 mega SI on sale and grab it!!