Vayne's Q IS NOT applying 2 silver bolts. It was a bug.

According to surrender at 20: [not sure on this, effect not mentioned on tooltip - Q enhanced auto applies two stacks of W - THIS IS A BUG, WILL BE GONE IN NEXT PBE PATCH]

So we are down to:

Tumble (Q): Bonus damage no longer crits.

Silver Bolts (W): Bonus True Damage increased from 6/7.5/9/10.5/12% to to 6/8/10/12/14% Minimum Damage changed from 40/60/80/100/120 to 50/65/80/95/110 Final Hour (R): New Effect: "While under the effects of Final Hours, Vayne is revitalized when enemy champions she has damaged recently are killed, healing for 20% of their maximum health Vayne must have damaged an enemy champion withing 3 seconds to earn healing."

This... isnt actually so bad. I think that she will overall be doing less damage to squishys, but more to tanks. Which is what shes supposed to do.