I recently added the SanDisk Extreme Pro Class 10 95 MB/S to my GN2. It is Wicked Fast! I did format it after I installed it. I have had no problems at all. However I will add that I suspect that the people having problems with their SD cards probably handled them incorrectly! NEVER let your fingers touch the gold contacts. Your fingers have oil on them, and NO (I repeat NO) you can not wash the oil off of your skin. Depending on the person that oil will be more or less detrimental to the connection, thereby producing all kinds of errors. I just want to slap the Customer Service Rep when they install the SIM card and put their grubby fingers on the contacts (This too will produce even more random problems with any phone). I ALWAYS warn them first. If you do get your finger on the contacts, use a Q-Tip moistened with (not dripping please) Denatured Alcohol to clean the contacts. Be sure that all is dry before using.