You shouldn't have to worry about bottlenecking from r/w speed of sd cards (for flashcards at least), but with the prices for class 10 micro sd cards with a large capacity, why are you considering anything below 48 mbps?Does microSD speed matter for DS flashcard on a 3DS? Such as ones with 30mb/s, 48/mbs, 80mb/s etc. The higher the better or is the flashcard bottlenecked at certain speed?