Migrating from Informix to Postgre

Hi Everyone,

I am a first timer in this forum.

We are currently using Informix and looking for a more economic database
solution(combination of Linux and Opensource database).  We currently have 5
database servers; 1 running on Sun E450(4 cpu), 2 on Sun E420(4 cpu), 1 on
Sun E250 and 1 on Netra T1, with database sizes 30 GB, 12 GB, 12GB, 15GB,
2GB respectively.  Databases on E420s are replicated between them.  There
are at least 10 tables which hold more than 75 million records and
fragmented accross different tablespaces. They have indexes and used
extensively in DSS type and as well as OLTP type of queries.

I went through lot of material in the discussion group but could not find a
straight forward answer for the following questions.  I would greatly
appreciate if someone can share your experience with Postgre.

1. How comfortably Postgre can support these databases( with respect to
volume)?
2. How reliable and what kind of replication Postgre provides? Is it log
based or transaction based?
3. Does it support table fragmentation accross multiple tablespaces?
4. Does it support raw devices?
5. I have read that it is transactional. But is it heterogeneous?  Can I
update multiple databases in multiple database servers of different family
(like informix, MySQL etc) in a single transaction?
6. How is the performance?

Thank you in advance

Dinesh