Mariano,
It is early in the morning right here and I might have read too hastily to your post, but from the diagonal reading I gave it seems you're going quickly to reinvent the wheel!
Those issues you rise are typical of database (engine) programming. Also, IIRC Smalltalk has another approach to persistence of objects called BOSS, have you given a look at it and check if a mix of Fuel + BOSS would accomplish your intent?
I think its implemented from scratch for one big reason: devil is always in details. Object format, streams, protocol and dozen of various things may differ from one smalltalk dialect to another one.
Also, i assume most of us are never heard about BOSS. Just googled it and found couple citations which related to VW world, but not to Squeak/Pharo. Is it runs on Pharo? What its license?
boss is a library in VW.
But by saying that, i'm a of course in favor of having more and more cross-dialect solutions.
for me larger autonomy. We do not invent by being forced to be compatible. If we are successful people will copy. Stef