All of the SVN shops I’ve worked in have a strict rule – replace all tabs with spaces, to avoid whitespace conflicts and variations of tabs in different editors.
Is this a very common standard? Does it really make a huge difference, and is it worth the trouble to push this standard to a group of developers new to SVN?
Unless you have a strict rule concerning spaces (and/or tabs), you should use tools that will ignore spaces when doing diff/compare/merge.