[XeTeX] bug or feature?

[Karl Berry]

    Could this feature be used to solve this problem:
      http://tug.org/pipermail/xetex/2009-February/011989.html
    increase the total number of different fonts one can use. 

The default in TeX Live is 5000 (as mentioned in the above mail).
I've increased it to 9000, and hash_size to 15000 while I was at it.

However, as pointed out, no limit is going to solve the problem of
every instance of [foo.otf] creating a "new" font.