Can't you use homebrew on your 3DS then? Flashcard work right? Correct me if I'm wrong, but there shouldn't be a problem for this? 'Cept for the rumor Ninty put out
Many flashcarts now run in ds mode on 3DS, so i suppose homebrews can run. This tool should be tested on 3DS in ds mode to avoid to saw off the edge.
What is in that edge anyway? Did they needed extra space for the board?
I highly doubt that, but I guess that 3DS card shouldn't fit in a DS so they added that edge.
No extra space needed, it's just to avoid the insertion on a ds/dsi/dslite.