On stage, I typically use x/y 90-110 degrees. ortf can sometimes give you a very exaggerated L-to-R image (panned so hard you have one instrument coming out of the L speaker, something else coming out of the R, thus preventing your speakers from doing that cool "disappearing act"). x/y actually gives the effect that the mics are a bit further away than ortf, but maintain the crisp clear dynamic on-stage/stage-lip sound. If you end up more than 10' from the band, I don't think ortf gives the exaggerated stereo image problem.