I hear you Sherm... when I got MSFS, I really never used my old sim again but I kept it on my PC for almost a year. until... and finally, I removed it and all of the supporting apps and scenery for it.. and gained over 2gb of space back!
On the XPlane front, investigate the ortho download requirement. From my understanding, for half descent quality, you need to download ortho tiles for the photogrammetry but better IFR if you like flying tubes.