Any Sennheiser experts here?

[project_c]

I have a very old pair of HD25-1 headphones, which I bought in Japan back in 2004. They've been great and had various parts replaced over the years, but they're starting to cut out from time to time and will get sent back to be repaired. In the meantime I'm looking through the current range and am trying to choose between the following:

HD25-II
HD6 Mix
HD7 DJ

All these look ok, I know the difference between the HD6 Mix and 7 DJ, but in sound tests the HD6's don't sound as good as the 25's. So my questions are:

1. Are the 25-II identical to the 25-I? No clear answers on this anywhere online, especially as the 25-I's are so old now.
2. Are the HD6 Mix an improvement on the 25-I's?

I use the 25-I's for both studio and normal use, they sound good for standard listening but I rely on them for mixing and studio stuff. The 8 DJ's will sound good but will not give me a flat response, and the 6 Mix's seem like they will not sound as good as the 25-I's, hence my dilemma choosing between those 3. Just thought I'd put feelers out here to see if anyone has any knowledge on any of this.