Also interested, and I'd be using homemades if I came. I would appreciate some guidelines for how powerful is too powerful, as I can tailor my arsenal to whatever is OK with you. I'd most likely be using a tagger-HAMP or a blowgun, both of which can be fired very softly as necessary at close range, but when fired hard will shoot a tagger about 50' flat.
My Alpha Trooper gets 70 feet max, and we use it every game with no injuries or complaints. Hell, NERF ELITE guns get between 65-75 stock. Your tagger-HAMP doesn't sound like a problem at all.
What about mini-marshmallows? Are these a viable type of ammunition to use?
No, standard foam darts/discs only. I apologize if this is a major inconvenience for you.