I have used SimpleChord for a year now and find it to be really valuable as a sketch tool to rough out ideas to be fully developed later in Logic Pro. First, it's rock solid; it's never crashed on me. With low machine overhead, it runs on my fairly old portable, so i can work anywhere. The user interface is simple letting me get a lot of work done quickly on developing chord progressions. I can play with some ideas, get a good idea of what I want, then go to Logic Pro to flesh out the songs.