[geezer]

.....Prior to the project I have just finished, all of the authoring was being done at the label....I was, and still am, sending them timecoded DTRS tapes (8tracks: 2 stereo, 6 for the 5.1) of 24 bit , 48k, no encoding. The label uses the Spruce authoring system.

The latest project , a promotional DVD for my brother's guitar company (PRS), we did entirely "in house" using Final Cut Pro and DVD Studio Pro on a colleague's Mac. The audio was simple stereo at 16/48 and AC3 encoded.
Albeit fairly high quality, you would still consider this an "industrial" quality product, unlike the the concert DVDs I have been doing for Image Entertainment.

I expect that I will start seeing the need to pre-encode DTS and Dolby Digital files over the next year or so on the in-house stuff.

SRC is, in my opinion, only just starting to work in the digital domain. I still don't trust it, and have been using D-A, A-D to get there until now (TC6000)....My new Yamaha console has extensive SRC, however, and I plan to test it soon.....SRC does seem to work better when simply halving or doubling.

Z-Sys certainly has a good rep, but I have not heard their SRC.

I think I would tend to process 96k stuff that will wind up on CD externally from the MTU rig.