Shown, below, 432 megapixels stitched, once cropped after assembly. The per-pixel detail falls a little short of the numbers, but it's very good. The idea I wanted to explore was whether the E-M5 Mark II, in additional to delivering image files of size far outstripping its nominal resolution—could those be used for even more stitched resolution to extend the envelop even further. After all, a 3 frame stitch can generally double the megapixels, which would yield 80 megapixels.
The obvious question is whether a future 50 megapixel “Sony A9” free of shutter vibration and sporting an E-M5 Mark II-style hi-res mode courtesy of the Sony A7 Mark II image stabilization could thus produce ~125 megapixel images (and having larger photosites, perhaps with higher quality too). It does beg the question of how such advances would compare to 50 megapixel conventional Canon 5DS and future Nikon DSLRs would fare and whether they would have continued relevance for landscape style shooting. At the least, the oversampling sensor shift approach of the E-M5 Mark II has potential for minimizing digital artifacts, and perhaps noise as well.
In spite of blocking the camera/tripod with my car, it seems that that hi-res mode of the E-M5 Mark II is not compatible with even a slight breath of wind (I expected this, pausing for the best lull, but half-pixel shifts of ~2 microns require absolute stillness). Still, the results are quite good, certainly if downsampled to 216 megapixels.
The main problem with such panoramas is the extreme aspect ratio; with more patience and better light, I’d have liked to shoot a dual-row panorama to include the foreground, and thus cutting the aspect ratio in half.
When I return from my trip, I’ll redo it from raw and see just how good it can be made (this version from the 40MP JPEGs produced by the EM5M2 hi-res mode).