Definitely some cash needed for that lens. But stitching isn't always the answer. Of course, it isn't really possible if any element of the scene is in motion or perhaps practical if taking a large number of shots. To Pros time is money.

That said, this lens isn't likely to find its way into my kit.

Btw, this thread reminded me of the group that stitched a huge number of shots of Machu Picchu taken with a 100-400. Great shot. File size was enormous.