PHP7?

Do you know if VW4 on XF1.4 works on PHP7?

I would advise against using PHP 7 in a production environment at the current time. VaultWiki 4 works with PHP 7, but there are still some serious bugs in PHP 7 that still result in random segfaults, infinite loops, and just unexpected behaviors. We have had to roll back to PHP 5.6 for a while.

On its own, XenForo 1.4 doesn't currently work perfectly with PHP 7. I never investigated if it's just a design conflict or if it's another PHP 7 bug, but you can't save most XenForo templates while using PHP 7 (segfault, always have to switch to PHP 5.6 for that).

Is VW4 ready for PHP7 Gold when its released?

We've been running PHP 7 here with VaultWiki for over a year now. We have not noticed any breaking issues in the past 6 months. If you want to use PHP 7 with VaultWiki, go ahead. Be warned, however, that PHP 7 will not work with vBulletin 3 or 4 without modifications to vBulletin.

I intent to use PHP7 after the migration to xenforo 1.5/1.6
First we will upgrade VW3 to VW4 and then migrate to XF.