I read about Yuzu and  N1-tri Voß as deciduous hybrids (both listed on Bernhard Voß old Website agrumi-voss).
Are there others?
Is Yuzu always deciduous?

With regards to your second question, Yuzu seems to be evergreen, or at least semi-evergreen here. I suspect it depends on the temperatures they experience.

okay. this would explain why it is listed as deciduous when grown in northern germany.

I found some hybrids described as deciduous. Has anyone experience with it?

c.ichangensis x trifoliata  N1-tri Voß
X639 Citrandarin
139 Eisenhut
Trifeola

I have most of your deciduous hybrids.

However this year is not the right one to be asking your question here.

We have had a total of 8hrs of frost this year. All for short periods just before dawn with the lowest temperature being -2.7*c (27*f). Day time temperatures being no lower than 5*c and up to 12*c.

Having said that one variety was quicker into leaf fall than poncirus and is more deciduous and I think another has also gone leafless over time.

I will have a look for you and report which plants are leafless and which have lost few if any leaves. A major caveat may be that we have had a stream of storms that have brought hurricane winds and biblical deluges, both of which will have contributed to defoliation.

I just read that a TaiTri can be deciduous, at least the one from eyeckr does.
link
I just wanted to add this, if someone is interested in this too...

Great memory Mikkel! You're right the TaiTri is totally deciduous for me. It kind of shocked me when I first started growing it when it dropped its leaves. I thought I killed it or something but realized that it just defoliates and goes into deep dormancy for the winter. I need to go out an look at it again when I get home from work but from memory it has cute, lacy, trifoliate leaves and a purplish buds before they bloom. I expect to have a good number of fruit this year.

My Yuzus are not always deciduous. They usually hold most of their leaves but during extreme winters they will totally defoliate. What I find interesting is that they can not only refoliate the next year but come back and still bloom very well.

New Spanish rootstock citrandarins FA5 and FA13 are decidous.
Also, sometime ago I got from Roberto budwood of PoncirusXSunki citrandarin. Last autumn its leaves turned yellow, and dropped exactly at the same time as of poncirus.