If classic becomes SMP friendly -- thread safe with a multi-threaded
client -- is there any reason to continue differentiation of the classic
and superserver engines? The only differences are whether the file is
opened for shared or exclusive access and whether locks (and blocking
ASTs) are exported. It all seems to boil down to a single engine
option: exclusive or shared access to the physical file. The only
significant difference is the garbage collection thread, which is a
mistake and should be dropped anyway.

If we can flush the difference between classic and superserver,
everyone's life gets a great deal simpler.

What am I missing?