Hey David,
I upgraded today to 11.25.0 and I can tell you, I'm glad I did. I've already noticed more options that weren't there previously. The new UI on this looks like it makes it much easier to manage than 11.24.x.
I have my doubts as well, but they were very persistent that I delete my MX records for the domain and just create an A record of mail.domainname.com and point it to the ip they specified... Thank you for responding, and if I do end up needing to go ahead with the XML-API/API2, I thank you in advance for any assistance you may provide.