GW Upgrades - Planning NetWare -> SLES/OES & GW8 -> GW2012

Hi all of you Groupwise gurus and aficionados,

We are ready (hopefully) to finally start to move off of NetWare for our Groupwise Post Offices. Would appreciate any comments that might be useful for the approach we are implementing, as follows:

Current GW 8.0.3 Setup:
Primary Domain and MTA on Server A with 3 POs on Servers B, C and D (NetWare 6.5) - 2 of them at remote sites (Note: I inherited this architecture)
GWIA Domain on SLES 11 sp2 (VM) with GWIA agent
Webaccess Domain on SLES 11 sp2 (VM) with Webaccess agent
Server B PO - 400GB, Server C PO - 90GB, Server D PO - 30GB

Proposed Upgrade Plan:
New SLES 11 server for new secondary domain that will be converted to primary domain. This will be the GW Management. First installed as GW8 and then upgraded to GW 2012. Nothing else will be on this server (VM).
Server B PO migrated to new, more powerful SLES 11 server (bare metal install) as GW8 still (NSS file system). Old Primary Domain which is now a secondary domain also migrated to this same server which will then run an MTA as well as a POA. Once migration completes and everything works under GW8, upgrade to 2012.
Server C PO (sometime weeks later) migrated to SLES (VM) as GW8 and then upgraded to 2012.
Server D PO (sometime weeks later) migrated to SLES (VM) as GW8 and then upgraded to 2012.
GWIA Domain upgraded to 2012 and then GWIA agent upgraded to 2012 (weeks later)
Webaccess Domain removed and new 2012 Webaccess installed (last thing done)

Would you do it any differently - or, any suggestions at all, based on your experience? Thanks, and have a great day!

Note: Ultimately, I would like to create new secondary domains at the remote sites, new Post Offices and then move user accounts so that we have remote POs with a local MTA, but we have some user mailboxes that are as large as 20-25GB so not sure how well that might work out.