I've been back and forth on this for months....buy V1 or spend a little more and get V2. Now I have a new dilemma. I use a Canon T2i. Do I really want to spend that much on this lens when I could upgrade my camera to something like the 5D mrk ii? Maybe I should buy a used V1 and save a little more and buy the camera too.
Depends on what you shoot. If it's NOT sports-centric, then I suggest the 5DII. IQ is better and you'd gain a stop or two at higher ISOs for the same level of noise. You might not need a midrange zoom, especially if you have a telezoom and/or a wide-angle zoom. Instead, you could get a fast prime, which comes in handy in low light situations.
I moved from a crop body to a 5DII earlier this year and sold my 17-55. I did not replace it with a FF mid-range zoom but use a 50mm prime instead. For anything longer, I'm using the 70-200.