I read the Raspberry Pi (1?) only supports transfer rates up to 20 MB/s. Does this statement hold true for the Raspberry Pi 2 B?
Would it therefore be worthwhile to spend any money on higher spec UHS-I U1 or U3 cards with maximum speeds of 90 MB/s?
Or could the same budget better be spent on a lower spec (just) Class 10 card (e.g. 45 MB/s) featuring a higher capacity (e.g. 64 GB SDXC instead of 32 GB SDHC)?
There are lots of benchmark results in this thread over at the raspberrypi.org forums. It certainly appears from those results that there's very little variance between the original Pi models and the Pi 2, and that the most you can expect from any SD card is an absolute maximum of around about 20MB/s. I believe this is a limitation of the Pi's SD card bus rather than anything to do with the SD cards, so there's likely not much to be done about it.
The max read/write speed of all the RPi's card readers are about 20Mb/s, some get a little more speed, but definitely nothing near 48Mb/s or higher. You should definitely save your money, or spend it better and buy a class 10 (or lower) card. I use class 4 cards on all my Pis, and it is snappy enough for my purposes.
