For what it's worth, this design is pretty much identical to an average  
frameless web page that has lists of links or other multi-column content.  
Those can work reasonably well, as long as it's clear to the user what's  
going on.

In other words, I don't think the idea is fundamentally flawed.  Though I  
would agree that doing so should be carefully considered, with some  
real-world data to back up the need.  Web pages usually wind up that way  
because it's too hard or complex to do it any other way.  Those  
limitations don't exist in a regular Windows application.

If the OP _does_ decide to proceed with the design, I'd agree that a  
regular UserControl with the desired controls inside it is a more  
desirable design.  The requirement using this technique to resize the  
contained controls according to the content is going to make the  
implementation messy, but at least it will present a nice,  
easy-to-understand interface to the user (as opposed to multiple  
scrollable controls, each without their own scroll bar but all scrolling  
in tandem with each other).

Pete