I am using Nikon and have been wishing (for years) that they come up with the equivalent of the Canon EF 70-200mm F4L IS USM.
From the reviews, this lens must be everything a prosumer hope for:
equally good build
constant "acceptably fast" and constant aperture
light enough for travels
But TS, you got to know what your main usage for telezoom
e.g. an F4 at 200mm may not be fast enough for sports; e.g. for our yearly F1 night race, you may not be able to "shoot through" the fence at ease