Move from one server with 2.1.9 to another server with 2.2.3

[throwaway-it at cox.net]

I did not see a reply to Martijn's inquiry.  I am particularly interested in question #2and #4 below, but in my case it's on a Solaris 5.8 (Cyrus 2.1.11) platform migrating to Linux AS 3.0 (Cyrus 2.2.12).
2.1.11 does not have the "xfer" command, 2.2.12 does.  Which release of 2.1.XX was the 'xfer' command introduced?  I did find it beginning in 2.2.3 (non-beta/alpha), I believe.  
Do I have to upgrade from 2.1.11 to 2.2.3 to be able to use the 'xfer' function?  The Solaris box is being replaced by the Linux box and prefer not to upgrade if possible.  Thanks.

  Bob
----------------
> Date	Mon, 03 Jan 2005 18:56:11 +0100
> To	info-cyrus at lists.andrew.cmu.edu
> From	Martijn <m2k2 at electronicsolutions.nl>
> Reply-To:	Martijn <m2k2 at electronicsolutions.nl>

>Hello all,

>I have a old server with Suse 8.2 and Cyrus 2.1.9 and have >setup new server with Suse 9.1 and cyrus 2.2.3.Using >imapcopy (disabled the seen-flag) I transfered the >mailboxes. On the new server folders without >messages/contents are not listed with listmailbox nor can I >set ACL permissions, cyradm will return the message >"Mailbox does not exist". Squirrelmail will not list the >empty folders. Thunderbird shows the folders in light gray >with italic fonts, it is not possible to subscribe to these >folders.
>
>My questions:
>1. Is it possible to "recover" these folders/rights?
>
>when not:
>2. Can I use the xfer/xfermailbox cyradm command to move >the mailboxes from 2.1.9 to 2.2.3?
>
>when this is also not possible:
>3. How to upgrade using the exist mailbox?
> I had a look at the /doc/install-upgrade.html doc but the >section upgrading from 2.1.x all wasn't to clear to me. I >think it is use full to upgrade the db since skiplist is >faster. There are files in the /var/spool/imap/ folder and >mailbox.db in /var/lib/imap/ is do I only need to upgrade >the mailboxes.db?
>
>at last:
>4. It would possible to do the tranfser again with the >imapsynch script. But will it work with cyrus version >2.2.3?
>
>Thank you in advance for any pointers they are appreciated >since this is fairly new to me.
>Martijn