Delegation Is Not Supported
SQL Server Integration Services does not support the delegation of credentials, sometimes referred to as a double hop. In this scenario, you are working on a client computer, Integration Services is installed on a second computer, and SQL Server is installed on a third computer. Although SQL Server Management Studio successfully passes your credentials from the client computer to the second computer on which Integration Services is running, Integration Services cannot delegate your credentials from the second computer to the third computer on which SQL Server is running.

Evil Kraig F (3/3/2013)

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Unlike Jason, I work in a shop where we have a dedicated SSIS box. There are benefits, but they're not readily apparently. However, it's also not a scalable solution like you're looking for.

Basically there's three reasons we run our SSIS on a separate box (well, vm instance, but same thing to us). First is memory control. SSIS runs outside the server cache and they'll compete. We keep a small engine on the same box simply for configuration controls and SQL Agent but that's it. Second is security. SQL Agent requires a large amount of rediculous control to create test jobs (to test network security for filepaths, doublehops, etc) and share them amongst a team (group ownership isn't allowed for a job yet).
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