My daily carry is a 10-20 and a 70-200vr along with a Tamron 90mm for macro. I'd really like something to fill the 20-70 gap (or most of it anyway). I'd really like it to be a constant 2.8 stop though. Should I fork over the cash for a Nikon 24-70 or are there good alternatives for me? I'd like to go FF in the future, but it probably won't happen for quite a while.