i irish dance and have been learning poi and while it's true, your arms are kept at your side for irish dancing and could presumably be busy spinning poi, i think in terms of rhythm, flow, and body momentum, it would be a weird combination. Irish dance is a lot about precision and tight-ness and while there is a certain precision in the flow of spinning poi (you know, when you get something dead on and it just feels right and then you can start riding out that flow and trying other moves), the precision of irish dancing is pretty different. Hands are kept at your side, because the focus is on your feet, you should always be up on your toes and your leg movements should always be sharp and quick. But! When I get really into spinning poi or hoops, I do find myself inadvertently up on my toes, and how I move across any area I may have is heavily informed by Irish dancing. It would be very awkward to try to incorporate poi into an irish dance, but I think Irish dancing can inform how you move your body while spinning poi, if no more than how ballet would.