I have been shooting all weekend with this lens and wish indoors I had the 2.8 but you still have to introduce flash or push you ISo to achieve reasonable shutter speeds. I am wondering if the extra stop is worth $1,000 more and double the weight for indoor shots or should I save that for the upcoming 24-70 ii release which is a much more used focal range for me? I do hate only f4 but 2.8 is not that much faster when under tungsten lighting. Yeah the bokeh seems nicer but I just have a hard time with the weight of that lens. How do you over come it?
Don't forget ab and back exercises. That thing can seriously hurt your spine if you sling it on your neck the whole day.
But seriously, only you can decide if what you'll get from the 2.8 is worth an extra grand. Probably yes if you're shooting professionally. Or if you have the money for it, does it really matter if it's worth it? Otherwise there's no need to get it, it's not as if it will make a night and day difference to your photos.