So, currently Rockbox uses "/" as separator in "Title" tag. But there are cases when this leads to last.fm scrobbler getting incorrect data. See:
AC/DC
DJ /rupture
tons of collaborations use / between two collaborating artists - the scrobbler gets only FIRST artist because / is read as a separator
How about a different separator? Current foobar2000 uses " / " (with spaces), scrobbling and library works awesome because people just don't use these spaces.