Cyrus operating system choice, RedHat vs Solaris

[Shawn Sivy]

I'm currently running Cyrus IMAP 2.2.x on a Solaris 9 SPARC box (a 
Sunfire V440 connected to an FC SAN).  It is running well with no 
problems.  I am starting to plan for an upgrade to Cyrus IMAP 2.3.x.  
Two questions:

1.  I am considering moving to RedHat Enterprise Linux 4 AS (on a 
Sunfire X4200 - AMD x86_64) connected to an iSCSI SAN (or maybe stick 
with the FC SAN).  Is there any pros/cons to running Cyrus IMAP on 
RedHat Linux configuration versus Sun Solaris SPARC configuration?

2.  If I do stick with Solaris, does Cyrus IMAP work well on Solaris 10 
or should I stick with Solaris 9 for now?

Thanks,

  -Shawn