Good questions.
What I would do with Ellie personally and what I do with her because her vet is only comfortable with withholding vaccines for so long are two different things. We are titering every year and after three years, even with a high tier, her vet wants to vaccinate anyway. I have not agreed so far nor have I declined. I think she does have a point in that there isn't much information on this yet. It is still in the lab... Challenge studies haven't even been done on DOI over 7 or 10 years I don't think.
If it were totally my choice, I would probably vaccinate once when the immune system is mature and titer a couple weeks later (actually Ellie's vet thought this would be nice to do with CDV) and then wait at least 3 years to even consider titering or vaccinating again. I don't think I would go her whole life with only one vaccine because as you said, DOI is still only at 7-10 years so far because challenge studies haven't been done beyond that. I would be comfortable only vaccinating with a low titer if I knew for sure that she needed it but since low titers mean nothing, they really frustrate me. After the immune system responds to the invader, there is no reason for the body to product antibodies that would be visable on titer.
So we don't know where we're going yet.
