Hello all!
Well, finally then, as the main developer of the 1541 Ultimate, I decided that it was about time to become a member of this forum as well.

Thank you all for the great interest in what was once just a hobby-project! Your interest in the product certainly helps to really finish it and add more exciting features!
Recently, I added 40-track D64 support, and implemented the REU (with 16MB, avilable on the Ultimate PLUS only

). I also did some bug-fixes to make it work correctly as drive 9, 10 or 11. Aside from working on the stand-alone version, I am currently investigating what's needed to support G64 (raw GCR format), and thinking on how to improve the sound output.
Some mentioned to me the use of JiffyDOS. There is no need to flash this; just put the 16K rom on the SD-card and call it "1541.rom", and it will automatically replace the built-in 1541 rom. Pretty much the same applies for the fpga logic itself and the file browser application. A newer version
can be flashed, but it can also just be put on the SD-card. Flashing is only necessary when one wants to boot the cartridge without SD-card in it, or often swap cards and not be bothered by which cards holds the Ultimate application.
You could always E-mail me, or post here with questions or enroll for the pre-order of the first production batch. Please let me know then also if you want to have the 'standard' version, or the 'plus' version with 32MB of ram.
Gideon