boot one time and then pull the SD card out, it will boot the same game instantly. when you want to switch put the sdcard back in. your save file won't be written to the sdcard until you load a new game.
Its slightly faster, just makes it feel more like a regular cart. No real downsides just click the sdcard back in when you want to change to a different game.
If you are trying to mod your pokemon save you need to launch a different game first then you can pull the save off the SDcard and do whatever you want then put it back, next time you load pokemon it will have the modded save loaded. The everdrive clone writes the save to sdcard when you load a new game. Until then it is stored on a flash chip. It writes the last games save from the flash chip to the SD card when you first boot another game and it writes that games file and save to flash that is why it takes like 30 seconds to boot. The SD card is not used while in game at all. Only while in the menu and when loading the game the first time. Even when you save in game it doesnt save to SD. All that to say, It re-enables the menu to be accessed and a new game to be chosen. No it wont pull up an old save. I carved the sdcard spot on mine to make it easier to get out, makes it feel more like a regular cart.