This is a good thread. Thank you Lars. I’ve had the wonderful blessing of
watching my body ‘grow’ in asana from age 16…until now, 52.
Part of the progression as we age is an ‘un-doing’ or sometimes a
’non-doing’ of asanas, and an increase of other yogic practices, as in the eight-limbs, i.e. 4-8.
Specifically with halasana, I practiced it relentlessly for many years–it was easy for me.
I did [I]not[/I] learn early on (from a number of teachers) to use support. 
[I]That[/I] is water under the bridge…
Later–in my 20’s–I began to study and
incorporate Iyengar methods in my practice.
I do not teach halasana and sarvangasana
without instructing on the use of props. Period.
Some students grumble about it; they ‘prefer’ without support.
I shake my head, roll my eyes, smile and say my usual speech about “risk vs. benefit”
After head, shoulder stands and plough, etc. for 30 years…I have finally given my neck a little rest.
For the past 5-6 years I’ve cut back those asanas tremendously.
I have to admit I’ve much less neck ‘issues’ than I used to have when I was younger.
Will I return to a deepening practice of halasana?
Maybe, if my intuition guides me there. 
…all that said…would I eliminate teaching halasana all-together? No.
I find it fascinating that it has been tossed out in Germany. Hmm…
I feel it is an asana of Hatha Yoga that has its place. It needs to be
addressed sensibly as the discussions aforementioned here in
this thread indicate. Sweeping it under the rug (so to speak)
won’t work as [I]“what one resists…persists[/I].”
Great discussion…
Best with Blessings,
Nancy