I don’t think there’s any scenario where QB hurts your chances. Colleges see Questbridge applicants as pre-screened for excellence, so even in the RD cycle, being a QB applicant is an advantage, although I don’t know any way to quantify how significant that advantage is.
The only possible disadvantage IMO is that you don’t get to weigh multiple offers if you get Matched. (And it’s a matter of opinion/preference whether that’s an advantage or disadvantage.) OTOH, there is no financial aid better than a QB Match offer.