Klaus, have you actually shot a pano with a 8mm fisheye lens on a 2.5-3sec continuous rotation?
Oh yes - i did
In my tests it looked pretty sharp . .
Which exposuretime did you use?
The point is to be able to capture fast action and street panos if one so chooses. If your ultimate concern is sharpness you can also use it to leisurely shoot supersharp bracketed scenes with a tripod.
It´s all related to the exposuretime and spin-time.
Exp.Time because the camera doesn´t stop as usual when it shoots. So depending on the spin-velocity you need at lest 1/1000sec. using a fisheye when you want real sharp shots. You also might use 1/500sec when you don´t want tack-sharp images.
Preferably you use an aperture which gives you some DOF. Let´s say f5,6/8 with a fisheye. So you need much light.
Rotatingtime: if it´s fast you´ll have a second poblem besides the exp.time: moving persons will appear multiple times close to the previous shot/stage of movement.
Rotating slower allows them to seperate better and so you can mask them more perfectly.
That´s why i suggest manual heads and fisheyes in crowdy places. I can set my Panoneed head for two different rotating speeds.
I used it here in speed-mode: http://www.360impressions.de/ArchivKoenigsallee2/
(right image at the top, called "Jui2012")
Took me quite a time to mask out moving objects (people, bikers, cars) in PTGui - APG´s masking tool wasn´t precise enough because the "ghosts" were close to each other.
Using a manual=slower head would have the ghosts seperated more and the masking would have been much easier.
(5D2/15mm fisheye, 1/800sec f5,6 and 5+1 shots @20%)