Having owned a 300 prime, several 70-300VR's and the 55-300 VR I'd happily suggest that the underdog holds its own against the more expensive lenses. Focus is a little slower, but good technique is everything with any equipment. It's so light that when on the D3100 it altogether weighs less than the D700 did!
Yes, the VR takes a second to spin up and settle - and while it's in motion it actually adds motion blur rather than curing it.
My recipe for wildlife shots is simple enough: M, 1/500, F/8, [+], [.], ISO Auto, VR off.
Manual mode or aperture priority with exposure compensation depending upon my needs, F/8 for decent depth of field, 1/500 for motion freeze (ideally 1/1000 but british light can be a real dog), centre point focus only so as to be most accurate, centre weighted meter because your subject is centre frame and that's where you need the exposure to be spot on. Auto ISO takes care of the rest so that I'm always on point with my settings.
Even with a 300/2.8 you'd be stopping down for depth of field, and f/8 is always f/8 regardless of the glass you're using.