Migrating from Oracle to Informix

Hello Net! In my software company, we have a pretty large application developed using Oracle as the RDBMS. Due mainly to business reasons, we came up with the idea to replace Oracle with Informix as the RDBMS platform. Without boring too much, I am talking about a 100GB database, with some 100 main tables and an additional 500 smaller ones. Some 1000 C/Cobol modules with about 5M lines of code. On top there are about 500 C++/PowerBuilder modules doing their own access to the database. Any help with the following is welcome: 1. Known problems with such a procedure. Some points which I am already aware are: different data types, no sequence generator, no array processing, rowID is different, etc. 2. Any workarounds for Oracle Forms (or CDE or Developer/2000) applications? Rewriting using New Era is an option. How about ODBC or open gateway? 3. Does Informix bring significant technical advantages to the table? 4. Assuming I am an experienced Oracle DBA. How long would it take to master Informix at a reasonable level? 5. Did anyone ever tried this? 6. Is this really a good idea at all? Ami