I just started experimenting with flashrom using a Dediprog SF600 this weekend. I noticed that there's no support for any of the 256Mb or 512Mb SPI NOR parts (4 byte addressing an issue?). Is there a newer version than 0.9.9 that I should try? I did find that the Google fork for chromeOS has a number of these parts (W25Q256, N25Q256, SST_25F256).
I would be happy to try an unreleased version & report results. I can also test with an FTDI232 based programmer. The boards I can test with currently have various versions of 25q512, 25q256, 25q128 and 25q32. Functionality with the smaller parts looks good.