Video part is not true actually, the highest bitrate for NEX 5N/5R/6 is 28Mbps (this is 28 MegaBITS per sec) while the minimum write speed of a Class 4 SD card is already 4MB/s or 32Mbps (8 bits = 1 byte), which is well above the minimum required speed. That's why in the manual it is stated min is class 4. Most SD class 4 cards will give you higher than minimum, I had a class 4 sandisk before, benchmarked it and it was writing at 7MB/s or 56Mbps, more than double the requirement for 1080p 28M.

So for video, anything above class 4 is overkill.

But for photos, especially burst mode (10fps  ) then lain cerita, cause how fast you can write to the SD card will determine how fast you can shoot continuously (assuming in camera buffer can tahan). And also of course higher SD card speed means you can copy to laptop/pc faster.. but I think that's not very important.

Sandisk extreme 32GB is only selling for RM96 after conversion at Amazon 
Updated note:hmm ok it looks like doesn't matter what card we use, it's 10fps then 2fps after that.... 

http://www.dpreview.com/reviews/sonynex5n/5