First, the disclaimer: IANAA (I am not an authority) on the etiquette of TMF, nor any other etiquette for that matter.
That said, here's how I see it. If you're not hosting the event, ask the host(s). If you're hosting, theoretically you get to set the local etiquette[1]. Assuming the policy for the event is totally up to you, my advice would depend on what you're trying to achieve.
If you're having a social gettogether with a group of people that you've already met several times, and want to introduce your SO and maybe meet some of theirs, that's great.
If you want to see some new faces, especially people that have never attended a munch before, then don't bring someone they would consider an outsider. For a potential attendee, there is value in knowing that everybody present is a ticklephile: they can talk more openly about their interest, and nobody will point and laugh and call them freaks. Rationally, someone who is already kinky and in a relationship with a ticklephile probably wouldn't point and laugh at the rest of us, but shyness is not rational. So if you're trying to convince that lurker on the edge of his seat, who is still embarrassed to speak of his fetish, that it's safe to come out and play, then limit the event to ticklephiles only.
By the way, congratulations on the new boyfriend! I get to meet him, right?
[1] Within certain bounds. There is a boundary beyond which DVNC will not help you organize it. Somewhere beyond that, he would ask you to explicitly state that your event is not affiliated with TMF. I don't think the issue of bringing an SO is that major.
