Vayne with Stormraider's Surge?

I'd personally say no. If you're doing enough damage to proc it you're ahead enough to not really need it. If you want to spend your keystone toward something that helps secure the win it could be the thing for you, but if you want overall reliability or something that helps more while behind I'd say no.

You'd be better off taking Warlord's Bloodlust or Fervor of Battle.

Edit: Oh, mixed Stormrider's Surge up with Thunderlord's Decree.

You could make an argument for it. Vayne can easily deal 30% of a squishy champion's health bar within 2 seconds later in the game so it may help with chasing, kiting, and escaping.

I still think Warlord's Bloodlust would be the better option though.