Only small experience, but we have four girls and a (obviously neutered) boy, and I think our boy stabilizes the group. He is the most mild mannered, he doesn't try to mount the girls, he just is a lovely, friendly placid pig who spends all day doing the Wiggly Bum dance, as he's so happy to see his girls!
I don't know if all Boy Piggles are the same, but I think he's our friendliest pig. And our combo works very well. I wish you could keep loads of boys together, as I'd have thousands!
So from my perspective I'd recommend a boy with girls, when we introduced him it was amazingly easy, like he'd always been there, no territorial behaviour AT ALL! Flob and Daisy were just like, oh, Hello! When we introduced the two girl babies (they must have been about 4 months old, the others were about a year at that point) it was much more stressful. They are all happy together now, but I think boy and girls works really well.