Subject pretty much says it all. Would be excellent to be able to tweak out the XML in the .svg file and the preview it before upload.

EDIT: You can put "*.svg" in as an HTML association and "shoehorn" it in there to get the Editor/Preview tabs (which is how I'm bypassing for convenience at the moment) but it really should preview from XML for it all to be done properly.

It certainly isn't dead; it can be somewhat slow. A new beta was released just a couple of days ago and (apologies for being off-topic) it looks like PHP 7 debugging will probably be released very soon.

For small SVG changes I set *.svg as XML then edit in PhpED and preview in an external browser. It's easy and quick to do an edit/save then reload in the browser.

You could add a Tools > Integration setting to open in an external browser.

For more involved changes I quite like using Adobe Illustrator.