I have some databases with a lot of tables and not had a problem, but not 800 of them.

but do you need one model with all the tables at one time ?

with most projects I only need to reference a few tables  from the db , we have say 20 sets of web services and many of them have models that only use say 10 or 20 tables out of say 100 or so.

EF does not force you to import every table.   so just add the ones you need, you can add more of them later if you need to.