Hi Markus,
I'm also trying to implement SD Card R/W over SPI, and have been somewhat successful. My problem is that my reads and writes are very slow (I wish I could get 8KB/s speeds!) and I continually lose the connection and have to re-init. I was wondering if you could let me know what parameters you are using to open and configure the SPI port? I am setting "Set Dataflow Method" to 2, "Set Master" to 1, "Set Clock Phase" to 0, and "Set Clock Polarity" to 0. I notice that you are using Phase and Polarity of 1, but I can't even get the SD Card to respond when I do this. I also can't get speeds of more than 1MHz, nevermind the 10MHz you seem to be getting.
Thanks for any help you can provide!
Jason