Hello Klaus,
With the recent closing of Kolor/Panotour, one of the tools that gained visibility is 3dvista, which surely you've seen before. IMO this guys have managed over the years to create a decent platform with a very lean UI interface, on first sight this one looks pretty advanced but on second evaluation, there's nothing there that krpano can't do, it could even be krpano based, well, almost.
After a dedicate examination of their offer only thing I found that is beyond krpano capabilities are the transitions among panoramas they offer, you can see those at "arrow hotspots" (http://3dvista.com/samples/animated_panorama.html) and in their "Live pano" option (http://3dvista.com/samples/live_pano_ny.html) which blend two scenes in a very smooth continuous way beyond of krpanos graphical engine.
Some months ago I developed my own "Street View Arrows" hotspots, which include a displacement animation to add that "movement feeling" at user experience(http://www.imagen360.com/360/senda-rupestre-touch/ FullHD touch screen experience, so it may not look optimal but let's you see the example). In that case I tuned the most the animations to be as close as possible to Mr. Google's, and in the end I noticed that Krpano wouldn't provide me the same graphical experience as I concluded it's graphical engine is different (correct me if I'm wrong).
I don't know how hard it would be for us to have the same (or better) kind of transitions but certainly is something I'd like to see in a future version as it would add that extra "3d feeling" effect we're missing now. Matterport has a similar smooth transitions among their spheres which also creates this wow techy factor, I know their engine is completely different but it's another example in the field of "modern virtual tours" just to ilustrate my point.
Thanks!
Luis