I bought Silicon Power 200x card and I got interesting results testing data transfer speed.
I did a basic test on my PC, using USB card reader. My older cards shown on the picture are rated 100x (PQI) and 133x (Transcend). They both demonstrate read speed of about 40 MB/s (reading large file from card to hard drive of my PC). However the card from Silicon Power has only shown 16 MB/s in my initial test with Transcend M5 card reader. I repeated the test few times with the same result. At first I was very disappointed, but when I repeated my tests with Hama card reader I've got the speed of ~44 MB/s from the same card!
The writing speed is approximately the same for Silicon Power and for 133x Transcend and is about 9 MB/s (100x PQI is notably slower).
I paid about 70 Eur for the Silicon Power card while the brand name 266x-300x cards are priced above 150 Eur, so I am very happy now with the saving I got :)
My main surprise is that cheap Hama reader overperformed the Transcend by so much - but only on 32GB card. The tests with 8GB and 2 GB cards didn't show a difference between 2 card readers. FYI Hama reader is a box from blue transparent plastic and called 'Cardreader 19 in 1'. It has partnumber 00055114. I've got one in Germany for 9 or 10 Euro. (The one from Transcend looks nicer - it's a square white glossy box in "Mac-style" but it failed miserably with large card.)