I made another attempt using strings instead of numbers, to get an idea of whether save.scm is usable:
$ cat persistence-test.scm
(use-modules (oop goops))
(use-modules (oop goops describe))
(use-modules (oop goops save))
;; Apply Andy's fix to the readable? function
(set! (@@ (oop goops save) readable?)
(lambda (x) (hashq-ref (@@ (oop goops save) readables) x)))
;; make a new class, make an instance of it, and show it
(define-class <ag-record> (<object>) name addr)
(define r (make <ag-record>))
(slot-set! r 'name "Fred")
(slot-set! r 'addr "101 Elm Street")
(describe r)
;; persist the instance
(define a '())
(set! a (acons 'r r a))
(save-objects a (current-output-port))
scheme@(guile-user)> (load "persistence-test.scm")
#<<ag-record> 9f2b2a0> is an instance of class <ag-record>
Slots are:
name = "Fred"
addr = "101 Elm Street"
(define r (restore <ag-record> (name addr) oop/goops/save.scm:423:32: In procedure #<procedure 9f64f48 at oop/goops/save.scm:414:21 (name aname get set)>:
oop/goops/save.scm:423:32: Wrong type to apply: #<syntax-transformer write-component>
... So I guess the answer is, "not yet".