The SD card speeds are great. The only thing you need to keep in mind is when you’re doing something that requires managing file paths and isn’t designed specifically for the Steam Deck. I ran into some headaches figuring out how to install the Vortex Mod Manager and get it fully functional for modding Skyrim on my Steam Deck’s SD card. I’m sure things have improved since then, but for people new to Linux it can be a slight hurdle if they choose to go outside the scope of typical Deck stuff.