Thats really a gud idea for it...but one of my concern is of indoor panorama. In the house the floor pattern should be patched seemlessly and that is where I'm getting more problems. Do you have some idea for that?
If you have PTP, try this. Stitch all shots except the nadir in APG. With the resultant equi image, use PTP to create cube faces. this will give you 6 cube faces, of which you are interested in the nadir face. Taking the nadir cube face and your nadir shot, combine them both using PS or any other photo editing software. Once nadir is "patched", re-import all cube faces using PTP again to create a completed and "patched" equi image.