If they are the only sources you need then you're all set. It's a very elegant solution to use D1 and D2 I think. If you had an analogue source then you'd need to think again.

VK, I forget which ones, but, I have a few DVD-A that don't carry a 2.0 track (something on Naxos and Natalie Merchant IIRC)

Rgds,
Nick