Originally Posted by JK98
Sandisk players sometimes have problems with class 10 cards(especially those not made by Sandisk), so using a class 4 card will have much less chances of problems. The card reader within the player isn't faster than class 4 anyway, so using a faster class of card won't load the card any faster when it is in the player(a class 10 card will load faster though if the card is removed and loaded using a fast card reader).
You don't hear about these card incompatibility issues with Rockbox, though.
iPod Touch 5G 32GB, Touch 4G 32GB, Clip Sport 8GB. Rockbox-> Clip Zip 4GB, iPod Nano 2G 4GB, iPod 5.5G 80GB
2012 Nexus 7 32GB, Asus MeMoPad 8 16+64GB, LG Optimus G Pro, Nokia Lumia 900 and Lumia 520