[sspies]

You cannot do graceful failovers with Route 53. This is, because DNS is a system of many dependend caching layers and the TTL value is not realiable.

[moe]

the TTL value is not realiable.

How is the TTL not reliable?

In my personal experience DNS cut-overs have never been a problem. Is there any major OS or ISP doing DNS wrong?

[sspies]

We have seen providers set the TTL value to 300 seconds no matter what. Chrome has been caching names forever while running...just two examples