Yeah, it works
Took me quite a while to figure out the reason for all those "undefined references", but it was a very small error in the end: I had forgotten to add libsfml-window to the list of libraries to which I link. Seems that it wasn't necessary with SFML 1.4, perhaps some functions were moved from graphics to window?!
Afterwards, I had to find out how to add another search path for dynamic libraries - LD_LIBRARY_PATH didn't work. ld's "-rpath" option is the answer
The performance with SFML2 seems indeed to be much better than with SFML 1.4 - though I can't make a direct comparison at the moment, as I uninstalled SFML 1.4 during my bug-search
Thanks again for all the help, and Merry Christmas