I have a Blackhawk Serpa and a MTAC Minotaur IWB for my P220 SAO, both of which I like very much.
Though I haven't seen one yet, the Sig Branded holsters look like a rebranded Fobus, which can be hit-or-miss in quality and fit. For IDPA purposes, the roto-holsters are not allowed due to their adjustable cant while on the belt as well as their offset/gap. Crossdraw holsters are also not allowed in IDPA.