Super telephoto zoom for good lighting

After much deliberation I bought the new Sigma 50-500 about a month ago. It's a lot of money, but the lure of a 10x zoom with Endbrennweite 500 mm was then too large.
After lens tests I have long wanted in magazines and on the Internet a few weeks rather vain. Only a detailed review I could find (Link here one must not call unfortunately). Where the objective was relatively well rated.
When the package arrived from Amazon (order and supply worked perfectly usual!) I was, however, but a little surprised by the size and especially the weight of the lens. Bolted to my camera, the Nikon D90 seems rather thin, which is why I have the same installed the supplied strap to the lens, and I would rather hang on photo tours this combination with the lens as the camera strap around your neck in order not to overburden the camera port.
After the first test shots was also quickly realized that my previous (cheap) was tripod with this lens hopelessly overwhelmed. Alone the mirror strike the camera offset this in such vibrations that despite mirror lock (of course with remote release) no really sharp shots with focal length 500 and longer exposure times were possible.
I'm using now, incidentally, a Manfrotto 055CXPRO3, with the ball head 468MGRC2.

Meanwhile, I was able to gather some practical experience with the Sigma 50-500; consequent findings:
(+) Due to the large zoom range is very well suited for Zoofotografie and Animal Photography lens.
(+) The OS is fast enough and good, even when compared to my Nikon VR lenses.
(-) Good light conditions for freehand shots and moving subjects but indispensable (at the D90 image noise at ISO 800 is too high to me).
(-) The light intensity decreases already at about 200 mm f / 6.3
() Slightly dim (f / 8 has been proven to me) is recommended, positively affects sharpness and CA (chromatic aberration, but is relatively weak) out.
(+) The AF is quick and accurate (with sufficient light).
(+) The maximum magnification ratio of 1: 3.1 (at 200 mm) can also make good close-ups.
() Is completely extended (500 mm) with the lens hood is the lens, probably due to the relatively far back seated Stativschelle, on a stable tripod already highly vulnerable to shocks or strong wind.
(-) A sealing lip on the camera connection (as with Nikon lenses available) would be desirable

In summary, I have not regretted the purchase, the new Sigma 50-500 provides a solid performance and given me opportunities beyond the my Nikon kit lens (18-200) go far.
Of course, more light intensity would be better, but the really high-intensity zoom lenses are far in this focal length range beyond my financial means.