I don't know Hg but I do know what little of Perforce I was once forced to use made me :(

Yeah, I must admit that Perforce is not that friendly. I did a lot of work related to it like writing some automatic branching stuff around p4 commands for example. But I think it'll be hard to do anything complicated with the help of `p4 help` or Googling around. Luckily we had the perforce book in the office. Does not have a 100% coverage but good enough :)