Subject Interbase Suitability

I am building a telephony system and want to use interbase as the
backend database. I used postgresql initially and ran into the
following performance problem. Upon reading the interbase documentation
I feel that interbase would lead me to a similar problem.

Problem Description
Each trunk on the system has a record in the database. The trunk stores
valuable statistics in this row (frequent updates). PostgreSQL creates
a new record on a UPDATE (something some database guru called MVCC).
Problem is self evident, a busy trunking system would probably do over
100 updates a second. Performance degradation leads to gradual collapse
and vacuuming the database is worse as it locks the tables and freezes
the system.

I found references to versions of rows maintained in interbase similar
to postgreSQL.

Can someone please tell me whether interbase would be any better for my
application? I have no idea how sybase/ms*/oracle perform under such

Thanks in advance
Nirmal Prasad R.