Enabling Block Chain Tracking with rman "Backup Optimization (ON)" on 11g R2, ODA X5-2 SAN

Hi MOSC,

In efforts to reduce resource need during rman backups, we are reviewing enabling block chain tracking for our weekday level 1 incremental backups.
Along side of that we have discovered that "Backup Optimization" is set to it's default of "OFF".  We'd like to turn that on.

A few high level questions;

1) For san / cluster environments, each node will have to be able to find,read,write etc to the BC tracking file on a common known directory.
Are there any other caveats or potential "gotchas" in using BCT that is not in the official Oracle docs?

2) We understand that enabling block chain tracking and turning "ON" backup optimization parameter will accomplish different but helpful tasks in the backup strategy.