The MODE7 now supports endlessly long worlds. Just keep adding GRPs and it will load them together seamlessly! It also runs faster on the New 3DS and is acceptable on the original 3DS with locked features.
REMEMBER, this is still in testing stages, but eZSB has lots of other features too. MODE7 will have proper sprite support soon. The lower screen's graphic layer. Ether use the keyboard or put a sprite over it)