Is this change specific to Oracle, or do other databases also allow the \ character to be used?
I was thinking of this as more of a compatibility option. Ie in openjpa < 1.3.0 we automatically append the ESCAPE clause (unless configured otherwise). In OpenJPA >= 1.3.0 we do not (since the clause seems extraneous to me).
I think this would be more tolerable for JDO providers who build on top of OpenJPA's kernel. They could set the compatibility option in their ProductDerivation (similar to what was proposed for detach options) and then all databases would use the old behavior. If the setting is in the DBDictionary then reverting to the old behavior requires more code.
To answer the broader question about whether we care for JDO in OpenJPA version x. My opinion is that we care, but our obligation is to provide JPA expected behavior by default. When this conflicts with JDO's expected behavior we should provide a configuration option to allow JDO like behavior, but we have no obligation to provide it "out of the box".