-1 on all accounts. I've only read a couple of reasons to do this and none of them are particularly compelling: 1) Sub-optimal performance - Only in the most extreme cases will this make any difference. In most cases, the time to search n more directories in the path to find a file won't result in any notable different. 2) Easier to understand - If you're smart enough to know how svn:externals works, you should be able to figure this out.
If anything should be done, then move the functionality out of the Zend class and into other classes and then depreciate the Zend class. Otherwise, this is just a lot of fuss about a very minor detail.
