The Gateway 3DS has gone into production and is available for pre-order. The team has reached out to me and provided a bit more information. I have quoted them below. Please read what they have to say and then discuss your opinions in this thread.
1) Yes, we are exploit based (Yay !?) and therefore very dependent on console firmware version: Our current plan is to release for firmware version 4.5 while continuing work on a solution for 6.x + after release. (please see note below)
2)Gateway will be shipped with 2 cards, the red Gateway shown in our video, which will handle 3ds backups, and a blue ds cart which will be used to prepare the console. ( more demo videos showing save game compatibility as well as setup procedures to follow soon )
3) Your console can be safely updated to 4.5 by using an original title released after March 2013 till current. Please double check the update message (version) before proceeding !
We currently have a very convenient and user friendly way to enter into our Gateway mode, while this entry point has been tested up to 6.0 we expect it to be shut off shortly after we release. We can not stress enough the importance of staying away from any further updates! ( 6.0 compatibility is only valid for our initial entry point, as stated in point (1) we currently only support firmware version 4.5 )
The Gateway 3DS team has reached out once again to answer some questions. Instead of making a new thread I am simply going to quote their comments as an update to this news post.
For save game, we are transferring and saving the save game onto the 3DS big SD card. So it is ok to swap titles using the same micro sd card.
Currently we have tested 4.2 , 4.3 and 4.5 and they all work. All games released after March 2013 will force an update to 4.5 (even backup roms). If a console is lower than 4.2 then it will need to be updated by using an original game released after March 2013. If a console is between 4.2 and 4.5 then there is no need to update, but when a newer rom is loaded it will force the update to 4.5 (again fine).
They closed their comments by stating that the launch is only a few days away. They hope to add updated support and more features shortly after launch.
Gateway 3DS Homepage