Jitter can appear on any digital interface, not just from CDs.
I never had a DTI. I knew someone who had one and he liked it alot. I think he was using it ahead of a DDE2.0 but eventually swapped out for a theta box. I had a DDE1.0 but went with another DAC before I could try the DTI.
There were a couple of versions of the DTI. I think the one to get is the 2 stage device (DTI pro-32 or something like that). I'm not sure if it would affect the DTI, but the AA DACs were widely reported to perform much better with the power supply upgrade. The DTI does strip SCMS. I used my DDE to perform format translation from optical to coax.
They seem to be pretty cheap these days so why not try one. I think that AA is long gone but the chip in there should be that Crystal Semicondutor chip and not much else. I never heard of one gone bad.