User blog comment:StrategicMagic/Vayne - Carry? Yes. AD? No./@comment-5425623-20120819153939

Interesting, but you should do the math to be sure. Silver Bolts are strong, but I wouldn't overestimate their usefulness in relation to a lot of AD in conjunction with attack speed and crit.

Such a build would also suffer against neutral map objectives - the Dragon or Baron would go down faster when a traditional AD build were employed.

As far as armor is concerned, Last Whisper tends to tenderize any targets that stack their defenses.

Against a target with 2000 HP and 100 armor, a Vayne with 300 AD and 0 ARP would, in 3 hits and 0 crits deal 900 physical damage, reduced to 450 by armor, and 220 (8% * 2000 + 60) true damage. If one of these attacks were critical and said Vayne were wielding an Infinite Edge, an additional 180 (150 * 1.2) damage would be dealt, resulting in 630 points of final damage as physical. 630 is nearly 3 times more than 220, and even as an AD Vayne, your attack speed should conventionally approach 2.0 attack speed (especially with a Nunu and Zeke's Herald).

Don't get me wrong, the true damage is still very valuable, but I think the reason most Vaynes tend to stick to the original build is because their priority targets aren't likely to rack up armor or health. In an ideal scenario, you'll have the enemy AD carry, AP carry or at the worst, a support or semi-tanky jungle / top in range, which are better disposed of by Physical Damage. Not completely capitalizing on attack speed also makes your Q a useful part of your rotation, as until you don't reach a certain speed, it'll refresh your next attack and boost your damage.

That said, if you're up against a team consisting of Swain, Cho'Gath, Malphite, Urgot and Soraka, then I'd be more likely to consider things like Trinity Force or Madred's Bloodrazor. Otherwise, I think the conventional inventory does just fine.