The payment will not be traceable.
Let's say TPB accept Silent payments. Someone sends them a donation, which confirms on-chain. Nobody else can know TPB is the receiver, because they can't know which on-chain address belongs to their Silent payment.
But what if I send a very specific amount. Then I could just look at the next block, find that amount and see to which address it is send in reality. So at least the sender can very easily verify the real address.
That is possible, but the whole point is that the address is mangled and used just once. That means it wouldn't matter that a specific amount is sent to an addresses - that's the only receive it makes anyway.
I see this as a feature mainly for wallets, not really for websites accepting BT donations as you can't really make the address update on each load without some PHP or JS running in the backend, and most people won't see a reason to make their addresses that cumbersome.