I also have EQ5 with no interest in upgrading it. I do enjoy using it on occasion, but I'm sure I don't use even a fraction of its capabilities. I'm a bit old school in that most often I will grab my colored pencils and my graph paper to plot out my quilts. But every now and then I do love to play around on EQ5, just not enough to justify upgrading it.
I'll be watching this thread though to hopefully learn from others how to better utilize the software.