Just to clarify....
THERE IS NOT YET ANY TOOL AVAILABLE ..., to dump or create backup of EBOOT, PHONE or CSC firmware currently in your phone..
Also, i don't have knowledge of any public-released official versions from this parts of a ROM specifically for I8000L devices.
As it is well known, you can relatively easy, create backup of the PDA currently on your phone, either it is I8000 or I8000L.
Also, PDA roms can be freely used interchangeably, between I8000 and I8000L, that is, you can safely use I8000 PDA roms in I8000L phones, and viceversa.
This is both for official (secany) or cooked PDA roms.
As regards CSC parts, you shouldn't really care since not any real benefit will be gained with updating with newer versions.
For the PHONE part, you shouldn't mess with I8000 phone part as it will likely mess with radio firmware and cause you network issues. I heard somewhere of people that flashed phone parts in I8000L, and worked, and also the opposite. So i would not risk, since you can't revert to original phone part (remember, they can't be obtained anywhere yet).
The same would do for EBOOT, HOWEVER .. after this new big '5 MB available memory' change in latest JA5 eboot, kind of deserves trying... one user claimed he did it (flashed JA5 eboot in I8000L) and worked fine... but AGAIN, you can't restore I8000L original EBOOT... so ... you get the point..