Yes I have Pithos and my wife (who did most of the bubble algae plucking in the family) absolutely loves them, I do as well. They're much harder to find than Emeralds but I personally think they are more reliable algae grazers. We bought one locally a few years ago and it took right to work eating mainly bubble algae but it also liked to sit on the sand, pluck a tuft of turf algae and pull it apart slowly eating it and then throwing the denuded sand particle over its shoulder before plucking another bunch. It was absolutely comical to watch. That Pitho only lived for around two, maybe two-and-a-half months though.
We liked it so much that we bought three Pithos from Reef Cleaners about six months ago. They destroyed the bubble algae. Out Foxface keeps most of the main rockwork pretty much bubble-free but it cannot get the ones down in crevices or in caves. The Pithos do such a good job that other than the occasional patch somewhere the Pithos don't go, like up on the back will ledges, my wife stopped plucking after the Pithos had been in the tank only one week or so. Now she will occasionally pluck a little crevice just to give the Foxface a treat. It follows her bubble-algae-wand (an acrylic rod with a toothpick scotch-taped to the tip) around grabbing the bubbles as they enter the water column.
I think we still have all three Pithos but it is hard to tell. They bury in the sand or go into a cave/crevice during the day unless they are very hungry and then come out at night to graze. Even though they are fair size, they are somewhat cryptic you can have one right in front of you on a rock and yet not see it until it moves. I saw one last night so I know we have, or at least had last night, at least one Pitho still. I saw a different one a few days ago so we probably still have at least two, maybe all three as two of them are hard to tell apart. The third one has a much lighter-colored carapace. Regardless, bubble algae is a non-issue in our tank since their introduction and I've never seen one bother anything in the tank except algae. I do not think they care for GHA though so they aren't an algae cure all.