As nobody from disinterested parties haven't left any comments yet, we'll try to post as neutral comment as possible.
Devart has longer EF support history - since Aug 30th, 2007. During these two years we have taken into account numerous bug reports and user requests. We also have created and ship with our products Entity Developer - a powerful design time tool.
We cannot call our Entity Framework support for Oracle an ideal one - this ORM was initially designed for MS SQL Server, so the possibility to take into account the marvels of other DBMSs is significantly limited.
It is enough to mention only the CROSS APPLY and OUTER APPLY problem.
But, in spite of these problems, most of our users are capable of working with Entity Framework successfully and comfortably.
That will be sufficient to say, but you have mentioned "critical enterprise allpications".
In this case we recommend you to take a look at our Oracle-specific LINQ to SQL implementation - LINQ to Oracle.
LINQ to SQL does not pretend to build cross-database solutions and hence allows to take into consideration peculiarities of a separate DBMS, Oracle in particular. Unlike Entity Framework, where we have only partial control over the generated SQL queries, in the LINQ to Oracle case we have full control over the process. This fact gives us an opportunity to generate fast and valid Oracle-specific queries and also speeds up bug fixing and improvement process.
In case of legacy Oracle databases EF usually is hard to apply, unlike LINQ to Oracle.
Design time work with LINQ to Oracle model is also performed using Entity Developer.