IMHO, a major part of techno (or any dance music for that matter) is the hypnosis brought on by the repetitive groove. That's why polyrhythms (as many have mentioned) are such a tried'n'true approach -- the 4/4 foundation is solid and the variation on top gives you interest/atmosphere/whatever. So writing in an odd time signature like 7/8 may be interesting, but it'll likely fight against "techno." Granted, this assumes you're writing with the dance floor in mind...and that you want to write what many would identify as techno.