We’ve been using ReiserFS as our default installation file system for
the last 6-7 years now, and it’s served us well in that time.
Unfortunately, there are a number of problems with it, some purely
technical, some more related to maintenance....

The solution for replacing an aging file system isn’t to switch to a
brand new unproven file system, but rather a proven one with a clear
upgrade path. That file system is ext3.