Hi all,
I tested PIVlab and a GUI I created using OpenPIV python, and can say that both perform about the same precision-wise. Both performed well on PIV Challenge 2001 case A (one of the more tougher images to evaluate), case B, and case E, PIV Challenge 2003 case A, and PIV Challenge 2014. This also demonstrates OpenPIV's new masking capabilities.
P.S. I think my GUI looks like PIVlab now :P (thanks to my obsession with it...)