D-Tools is a pretty damn powerful tool, maybe overkill for alot of aplications. If you have alot of Visio experience it won't take you too long to get into it. Properly set up and tweaked, you can pretty much run your your entire business of it. If you are going to use it as a design and business tool, you really have to commit to it.
My tried and true method for blocking systems preempts D-Tools.
If you are familiar with Visio, it shouldn't take you too long to make you own custom stencil with your commonly used items.
Yes. RackTools is damn handy....and free.
www.racktools.com (requires Visio)
Happy Stencilling