I'm planning on buying a new DLT or SDLT recorder to act as both a backup for my video files (600 GB) but also to make mass quantities of DVDs at a duplication house. Will the dup houses accept SDLT or is it incompatible with DLT? I've emailed the manufacturers but I'm not sure they'll give me a straight answer.

Only the replication facility will be able to answer that question.
Even if others support it, yours might not. So if you decided on
a facility make sure you talk to them about this.

Is SDLT also a different tape format or can it work with DLT tapes
as well? In that case it *might* be backwards compatible.

I do believe that some facilities these days also accept DVD
video or rom as a source (where for dual layer you would have
two DVD discs). Ofcourse that will also depend on your facility.

Contact them, they are the only ones who can sort this out for you!

I'm amazed at how many duplication houses advertise that they make duplicates from DVD and bury the DLT and SDLT options. I haven't had to mass produce until now and have always heard DLT is the standard. Thanks, Rob.