There is no requirement of professional programming tied to any warranties on Universal Remote remotes. What they do say is that you need to get the Pro line of remotes from an authorized dealer, and there are no online authorized dealers (I don't believe). So if you get the remote from some unauthorized place and then have issues you may be up the creek.
As for Harmony vs. Universal Remote, the MX-450 coupled with an RF system will smoke Harmony in terms of how powerful it is. The Harmony, conversely will be easier to program, though the MX-450 isn't terribly difficult to manage.
What you should really be interested in, however, is the
Digital RF-50 which is the consumer level version of the MX-450.
Our review:
http://www.audioholics.com/reviews/remote-controls/universal-mx-450-rf