Unfortunately, the way the JPA connector is written in 2.x means that the connector (and JPA) end up loading some of the binary values even when not needed. I'm not sure if we can easily change that for 2.7, but the situation is definitely changing in 3.0. For example, I'm nearly finished with a feature that dramatically changes how we're dealing with Binary values. With 3, content of a binary value will be loaded only when using the binary's InputStream to read the content, and even then it will be streamed/buffered from the underlying storage. Similarly, creating a new binary values is also done with an InputStream, and will also involve streaming to the underlying storage.
IOW, in ModeShape 3.0 the binary values will never be fully loaded into heap memory.
When is the ETA for 3.0 supposed to take place?
Is there a chance to access the source code for 3.0?
We plan to release our first alpha in a few weeks (before the holidays), another alpha in early January, a feature complete beta by mid-January, and go through a few more quick betas before the final release in mid-to-late February.
As to the source, we're working in the '3.x' branch of our main Git repository, but it's a bit of a mess as it includes both the new stuff ('modeshape-jcr-redux') and the old stuff ('modeshape-jcr'). Before we release the first alpha, we'll remove the old stuff and move the new stuff into 'modeshape-jcr'. We're redoing our documentation, and what we have (which is not much yet) is available here.