I've never liked the pixilation effect, and have read that there is software that can defeat it if someone wants to bad enough.
As a photo hobbiest, the only times I've photographed ladies who don't show their faces are ladies I already know who ask me to shoot them. That's because I'm more interested in faces than pretty much any other feature for purposes of photography.
This shot of AngelaS is a partial crop with blur vignette and some burning. She was pleased with it (very sweet lady by the way):
The very first lady I shot was Meg "Hotlips" who moved away, but I lost the images in a hard drive crash. We didn't have any masks available, so I digitally cut a piece of the sheepskin rug she was on and created a mask in photoshop. Some of the Mardi-Grass masks are nice, but I've never used one.
I also got an antique hand mirror to use as a block, but again, haven't used it.
In summary, eyes can be a problem for anonymity, so a mask is pleasing to look at but not the most secure.
To be sure, crop.