For me a big issue would be the smell...if you hang around smokers your kilt will smell like, well, an old ashtray. I'm very fortunate to live in a town that bans smoking in all public places, including restaurants and pubs, but when we go elsewhere I quickly remember what it was like back in the day.
A synthetic kilt is washable. I think that would be a much bigger plus than the possible "flame on!" that could occur. I'm really conflicted here as I am essentially done with acrylic kilts, but if you are really going to be in a smoky environment and don't want to smell that way in perpetuity, a washable kilt may be the way to go.