I have a new D7100 showing up tomorrow. In its bundle, I am getting a 32 GB, 80 MB/s memory card. Now, Saturday I am selling my Sony A57 which has a 32 GB, 22 MB/s memory card. My question to everyone is: should I keep this old card as a back up or let it go with the camera and buy another card. Will the slower read/write speed be too slow for the D7100.