> Why would you depend on the exact value of the identity hash?

Not the value of the identityHash, the value of the hash.

> When writing a new image and the identity hash changed, then obviously all dictionaries would have to be rehashed. Seems like a non-issue to me.

That's the exact problem I want to avoid.  Think in the context of a
multiuser client-server app accessing the same large persistent domain
model.  The domain model includes a complex domain object used as a
key in a dictionary, and one of the attributes used to determine its
hash is one of its boolean attributes.

Now, some of the clients suddenly happen to get a new #identityHash
for true, which in turn changes its #hash.  Now they cannot access the
domain's whose hash depends on true or false.  Worse, they might
#at:put: into it and then the model is "corrupted" because there is no
universally-consistent notion of true's hash across all client images.

You're right, I could add my own private extensions, but we should
consider having "universal" atomics given the the aforementioned
insidiousness of the above situation..?