In an article in Linux Journal (February, 2000), Eric S. Raymond says that the next market to be entered (perhaps conquered?) by Linux is the desktop users market. In this author's opinion, KDE is the clear choice for taking Linux to this market. KDE 2.0 delivers a mature, robust, feature-rich set of desktop applications and utilities, including an office suite, KOffice. This suite fills a long-lasting void in the Linux free software world that has been crucial to keeping Linux off of many desktops.
I suspect you'll find that programming with KDE will give you a much larger audience for your applications, will result in decreased development time, and will provide hours of enjoyment. I hope that this book will add to the enjoyment.
Good luck with KDE. You are doing The Right Thing ;).