It's actually completely beneficial for you. You save space so in return you can fit more roms. Some older rom trimmers can damage Download Play and Wi-Fi but the trimmer in the link above will not damage your game. You should use it.
Just stick a shortcut in your "Send To" folder so that you can right-click a bunch of them and trim them all at once. It won't overwrite anything, it'll just rename the trimmed roms.
Please post any contributions to the original topic that I ported this code from;