Lucanica (and pollushon),
Here are a couple of other sites:
They have firmware for Sony DDU-1611, 1612, 1613, 1615 and others. I assume "fast read patch" and "slow-and-quiet" let you adjust reading speed. Click on "utilities" for some really interesting stuff. Flashing programs there may let you save the factory firmware to flash back if things don't work out.
And since many Sony drives are really rebadged Lite-Ons, their program to make your drive region-free or reset the region changes may be just what you are looking for (after X changes, the drive normally won't let you change the region any more). This may void your warranty, but save you the cost of buying a DVD-Rom (or DVD R/RW) for each region.
The "links" page has even more resources for Sony and Lite-On. Looks like these guys have definitely done their homework!
Here's another resource:
The Firmware Page
They have forums, utilities and links as well. Very impressive.
Sorry I couldn't get bright colored, annoying flashing URLs and smilies, but this helps me get the word out sooner. Let us know if this helps!