[Leica] Apo 280/2,8 ?

[director@ubi.edu]

LUGers,

I don't want to restart the UV war, but I have a question.

Leica use to sell the two first versions of the 
Apo 280/2,8 with a huge filter E112.
(I don't know about the new modular system)
In the Instructions manual they say:
"As the surface of the front lens element is sensitive
to outside influences despite its hard coating,
we recommend the use of the colorless neutral density filter
(NDx1, no increase in exposure time), wich is part of the
standard lens outfit.....
... Attention : For special light situation (e.g. light
sources in the picture or backlight) we recommend
working without a filter."

Question for those who really use that lens:
Do you use the filter?
If you do, do you see any difference in term of results ?
If you don't, is the front element so sensitive ?

BTW if you have any other comment about that lens,
I will love to read it.
Somebody make me an offer that you can't refuse,
and I try to make the right decision.
:?)

Thank you in advance to share your experience.

Lucien