I always open raise potsize when folded to me or when there is one or more limpers. On the BTN I 3x it. I play PLO10. 

I see alot of different preflop raise sizes in videos. Phil Galfdond 3x'es it unopenend or even against one limper. He also has 'weird' preflop raise sizes like 2.27 bb and 2.77 bb. What are the pro's and cons of this? Can't find much theory about it. What are your thoughts?