architecture for querying json and json-ld

I know the topic "mongodb and json-ld integration" has come up a few times
in this list, but our group is trying to make a decision regarding an ideal
architecture and so I thought I would get your input. Here is the scenario:

1. we have a ton of data on mongodb, but now we need to enhance a portion
of it with ontologies (at this point DC, FOAF and bio2rdf/mesh). we will be
relying heavily on sparql to make some inferences
2. while we could have mongodb side by side with a triple store such as
Allegrograph, it would be easier to keep the whole thing under a single
database
3. to my knowledge, I can run sparql queries on mongodb using
http://franz.com/agraph/support/documentation/v4/mongo-interface.html but
couldn't find much more on the limitations of this approach

the questions:

1. is the allegro extension above still the best way of bringing json and
json-ld together under mongodb
2. any other sensible approach that could be attempted here

this is the short description of my case, I can provide more info if you
would like

many thanks