IMO namespaces are *not* directories and should always be referenced with backslashes. What works versus what "should be" vary quite a bit, but in this case the slash directions don't really matter because `view()` uses FileLocator's `locateFile()` which has the following code:
PHP Code:
// Standardize slashes to handle nested directories.
$file = strtr($file, '/', '\\');
... which replaces all forward slashes with backslashes prior to executing the lookup. Bottom line is: backslash is more technically correct (opinion), either slash will work, backslash requires escaping.