Large Filesystem

Hi All,

I am currently in the process of building a large filesystem with
12 x 6TB 3.5" SAS in raid6, effectively ~55TB of storage, to serve as a
central, mostly download, platform with around 100 concurrent
connections.

The current system is running FreeBSD with ZFS and I would like to
see if it's possible on OpenBSD, as it's one of the last two systems
on FreeBSD left. :)

Has anybody build a large filesystem using FFS2? Is it a good idea?
How does it perform? What are good tests to run?

Your help and suggestions are really appriciated!

Mischa