If anyone knows how many of these were made it would be John Foster at www.biofos.com.
If you want to get some nice hand held color shots, Provia 400 can be pushed two stops with very good results. My problem with holding long, heavy lenses isn't so much getting the shutter speed fast enough, it is getting the focus and framing right when the shutter is snapped. I'm sure this is an excellent lens, but for practical purposes (and the few times I have need of a long lens) the 200mm f4 and wee f5 are much more practical. Add to these the T-CONs made for the IS System and you can get from 300mm to 380mm with almost no loss of aperture.