@Stefan:
Thanks for your feedback.

I believe that going for a multi-property expression would be a
more radical change for the current url syntax, which actually is quite 
nice. So it is way beyond this issue, I guess it best should be brought 
up on the development list.

Sascha now wrote that he supports the other backends now as well.
So I am still faced with the question: Shall I committ it to trunk?