I know Adobe is a bit of a dirty word around here but today's update to ACR and LR introduced a new feature which seems very powerful and useful for those that do stitches. Lots of new lens profiles and normal stuff too, but it seems to me Boundary Warp is a genuinely new feature.
http://blogs.adobe.com/jkost/2016/01/adobe-camera-raw-9-4-and-lightroom-6-4-are-now-available-with-boundary-warp.html
http://blogs.adobe.com/jkost/2016/01/adobe-camera-raw-9-4-and-lightroom-6-4-are-now-available-with-boundary-warp.html