I've never used Arbortext, but I will give you the pro's and con's of my experiences with UD4.
Pro's
HTML coding - tables, pictures, etc. is an unbelievable snap.
ASP - drop and drag makes any newbie to ASP look like a pro.
Overall - a very powerful - yet pretty user friendly program to use.
Fair amount of user groups to help
Con's
HTML Coding is so simple - you tend to forget the basics of doing it by hand.
ASP - horribly inefficient code. Tough to troubleshoot by looking at the code itself. it's more of a one-size-fits-all. If you want to become proficient at coding on your own - UD4 will not help you along.
you'll find even more user groups for just ASP.
Comes down to easy versus flexibility