Although, currently (Oct 2013 kernel 3.11.6), My T520 boots in "Discrete Graphics" still only when i ease the GRUB2 framebuffer but do not set any mode nomodeset kernel options.
Although, currently (Oct 2013, kernel 3.11.6), my T520 boots in "Discrete Graphics" mode only when i disable the GRUB2 framebuffer, but do not set any of the nomodeset kernel options.