Informix 7.2 Under AIX v.s. Informix 7.2 Workgroups Under NT

We, like a lot of other companies, are currently making plans to ensure that our systems will operate correctly in the next century. Since we are currently using 4.1 and Informix doesn't plan to implement the DBCENTURY capability in that version, we are planning to upgrade to 7.2. I have heard that our Informix rep. is recommending that we go to their Workgroup product instead of SE or Online because conversion is easier. Does anyone have information on upgrade considerations on either of these options? Does anyone know why it would be easier to upgrade to the Workgroup? Has anyone heard anything about Informix's plans to continue to support SE? I've read the FAQ entry on 4.1 to 7.2 upgrades so there's no need to repeat any of that. I would really appreciate your comments on this. Thanks.