If the menu gets better, and loading speed increases then MK2 would be almost as good as an MK3, because by then, most games will run at full speed from the SD card.
Honestly, the feature of the internal memory of the MK3 is over estimated IMHO, in fact I never use it.
With 256 Mb(my version at least) it's not enough to run some games(64MB and over) and even if I flash something smaller into it, it takes a long time to burn.
Certanly compatibility is improved a lot then, bu then again I'd rather see faster reading times from the SD card to run games directly.