files only. for the following reasons: it avoids the need to have a Sql Server installed and running as part of the ET solution (frees up memory,much simpler to deploy...

It depends how much time you are willing to waste I think.  SSIS is totally different than DTS.  Totally.

it pays to remember that SSIS is very type-sensitive and will never do implicit conversions, where DTS did a ton of them for you.

there was an answer to this exact question recently on the microsoft ssis forum.  go there and search for mulit-step or similiar and you should find it.  IIRC it is...