Your selling approach should not be on the tool, it should be based on what their problems are and how you can fix them. If you decide to use Kentico as the tool to fix them, spectacular! If you use Kentico and another tool to fix them great. At least you know your tool sets and what they can and can't do.
My experience being technical, I can say, development is your simple asp.net project or website. So it really didn't take a long time for me to adapt to it whereas with some other CMS solutions I've worked with have been very difficult to adapt and code to.
As David mentioned, contact Bart or someone in sales as the will do some of that leg work for you if you're a new partner/customer.