The work flow is this:

> 
> JPEG orignal-> Edited in Photoshop->
>  EPS-> Imported into a InDesign
>  document-> Distilled to PDF-> Sent to
>  printer
> 
> 
> 

My question is it necessary to save it as the EPS in the step between Photoshop and InDesign? It would seem to me that keeping it as a JPEG at this step would be fine (and much smaller), and the conversion to EPS doesn't really gain anything. 

Am I missing something other than lossy/non-lossy about an EPS that makes it better for this?

EDIT:
Lots of good information in the answers.

My reason for asking is that I'm concerned that a 4mb original expanded to a 40mb+ eps times many files equals a lot of additional storage for marginal additional benefit.

**To look at this another way, if the original JPEG is otherwise already perfect is it necessary to convert to a non-lossy format first?** 

The RAW vs JPEG debate among photographers is ongoing, but when you start talking about press ready material, it seems to be "JPEG lossy therefore JPEG evil!" Beyond this there often doesn't seem to be much thought about what lossy means in practice. From what I've seen, a single edit to a high resolution JPEG isn't going to make any practical difference.