I have been quite busy with some work laterly, but I was muching around with acidfree which looks like a cool (if I can every get the bloody thing to work), and noticed that it was linked with a module called filemanager. Now filemanager from my brief look, seems to do everything that I want fscache to do and more.
So with a bit more playing and I think that I am going to change filestore2 to use filemanager instead of fscache. I need to do a lot of work on both filestore2 and fscache to bring it upto scratch for Drupal 4.7, but with a few minor changes I should be able to link it into filemanager and leave fscache behind.
If all goes well I may even do this for 4.6 and backport filestore2.
At this stage it is going to be a few weeks, and I am hoping to catch on some of my projects during the Christmas break, which will be fun.