Having looked at it for like 30 seconds, they look to be pretty similar. One has 2x the number of stocks, but the concentration of both funds will be in the higher cap stocks that are going to be held in common between them. From the perspective of short term performance, my guess is that they will be very tightly correlated.
I'm not a tax advisor and not providing tax advice. I personally would feel OK trying to claim the tax loss on this sale. Worst case is the IRS disallows it. But my guess from reading other articles on the subject is that it would be fine.