I've had to abandon plans to use Extra Lazy Collections for the following reasons.

We have use cases where when we check for the existence of an object we are comparing equality based on natural identifiers using contains and equals. So with a one to many relationship you iterate and use contains on the collection to check if you've already seen the object your currently processing and it's already been inserted.

This works fine with a Lazy collection however with Extra Lazy Collections this doesn't work at all when you're using sequences for the actual primary keys of these objects. This is because obviously when you're comparing an object that has no identified to one that does the implementation of contains on a Extra Lazy Collection uses the actual columns associated with the join relationship b/w the two entities and to complete such a join you use the sequences as the values. Sequences are simply not known when all you have is the natural identifier state to make your comparison.

So you're forced to incur the initialization of the collection just to check existence.

Therefore Extra Lazy Collections simply cannot always replace Lazy Collections and seem to only be applicable when you identifiers are based on natural keys.