Even if you don't - if you might rent a DAT recorder (like I'm doing this thursday) or you have people bringing gear into your studio it is worth it.
It gives you that nice flexibility...
If I had to guess, you're debating between the Delta 44 and the 66... I went with the 66 since I figured that sooner or later I'd want the S/PDIF (how the hell do people pronounce that anyways?) and sure enough, it is barely a month later and I'm glad I have it. Sure, I got transfer via analog, but why??? Stuff went through an A/D to get into the DAT, why run it through a D/A then another A/D to get it out?
That's two more potential spots for the sound to potentially get crappier.