Thanks for the info!

But if he's aiming to save up space the safest and fastest solution would be to use cia files instead of ROM'S.
sure, but if they are trimmed as much as they can be i guess they are pretty much the same size...? surely very close at least.
plus you don't have to wait super long to install them with devmenu (although you can put lots of an sd card and do it while you sleep)
i don't like that i need 2 gb free on my sd card to install a 1gb game, since the cia takes up 1gb, then the installed takes up 1gb. (sure i can delete the cia afterwards)
personally, for eshop games i use the cia if available, and for retail carts i use .3ds rom with gw
whatever choice, the games are still fun
