PostgreSQL 9.0 High perfomance

I've just finished G.Smith's "PostgreSQL 9.0 High performance". It's just an excellent book for any DBA. It provides detail information on PostgreSQL-related tuning (from server hardware and OS settings to query tuning and DBMS monitoring). We are going to upgrade our DBMS server next year, so I'll have an opportunity to apply this recommendations in practice. The only disadvantage is that the book is Linux-oriented, and we have FreeBSD DBMS server. However, basic settings for our OS are also covered in this book. Now I wonder: should I use ZFS for PostgreSQL on FreeBSD? I think at least I should make some benchmarks...