Upload & Sell: On
FWIW, the Lexar 400x SD cards look to be pretty slow in some tests.
The Lexar 600x were almost as fast as the Sandisk 80 Mbs cards in a Canon T4i test, and tied in a Nikon 7100 test.
The 32Gb 600x are $50 for 2 right now.
The Sandisk 95 MBs look to be the best of the Class 10 cards in almost all tests, but the 80 MBs and then the 600x aren't too far behind. (There are some anomalies on different tests, in different cameras.)
The Lexar 400x SD cards at $20 are only 40% of the speed of the Sandisk 80 MBs & Lexar 600x cards in one test (in a Nikon.) They were about 50% of the speed of the Sandisk 45 MBs.
Obviously YMMV. There are lots of numbers and tests out there. I only looked at camera write speeds, not computer read speeds, etc.
Nikon 7100 test by http://sportsphotoguy.com/d7100-raw-burst-test/
T4i buffer test with Sandisk 80 MBs, Lexar 600x, and PNY Elite - fastest to slowest -by http://thewirecutter.com/reviews/best-sd-card/