But, as per here - http://msdn.microsoft.com/en-us/library/jj163800.aspx - "Not all functionality that you find in the Microsoft.Office.Server.UserProfiles assembly is available from client APIs. For example, you have to use the server object model to create or change user profiles because they're read-only from client APIs (except the user profile picture)"
That sounds like there's no supported solution for programatically updating user profile fields.. other than a sandbox solution/aspx page with codebehind running on the server. But with sandbox solutions deprecated (and farm solutions presumably not an option because I'm on Office365), does that mean there's no way of doing this?
Re: sandbox solutions, it's something I'm avoiding at all costs; else we're literally building a solution which will stop working in one or two product releases/versions' time when the deprecated feature is actually removed.