Filesystem and PG configuration

[RBN <rbn.ggl@xxxxxxxxx>]

Can someone suggest some appropriate initial configuration parameters and shared memory settings for the following hardware?  

I'm running Debian on a Dell with 4x6 core CPU and 128GB memory and writing to  a coraid with 9 x 32GB SSDs RAID 10 using jfs with 8 drives active and 1 as spare.  

I'm considering changing to xfs.  I'm not sure what block size to use for the file system, is 8192 appropriate?  The OS page size is 4096.

The database is both write and read intensive, with about 750MB of new data added per week and old deleted every six months to one year.