I got an answer from Bernd Raichle about his opinion about switch to
new patterns. I can explain more later, but:
(a) he asked for some more time (he prefers not to switch before TL
2012 is frozen)
(b) there should be some way to switch to the old patterns if default is changed
(c) he will do some research & ask on a few mailing lists etc.
I have three questions/requests:
1) Connected with (b): is your team willing to add support for the old
patterns to "hyphsubst", so that one could use the same mechanism to
switch to the old patterns as one uses nowadays to switch to the
latest ones? This means that hyphsubst needs to be aware of those old
patterns and then either dehyph-exptl could ship old patterns or they
could be unconditionally included as part of TeX Live core in the same
way as they are now. The two files would probably have to be slightly
modified, so that loading german-x-old (or whatever the name would be)
would not break XeTeX & LuaTeX.
2) It would be nice to have an article and a "word list" with
differences somewhere at hand, so that any interested user would be
able to check the differences in breakpoints between old & new
patterns on a long list of words. (The important part lies in "only
the differences", not all the words from vocabulary. And even then
there could be one complete list and a shorter one for those who would
only like to glimpse without checking thousands of words.)
3) Do you have any rough estimates about when the patterns will more
or less stabilize? They don't need to be 100% frozen, but if you still
expect a significant amount of changes, it might make sense to finish
them first before changing patterns in the core.
I cannot promise anything, but it helps if you have answers at hand
when other German users start asking questions.