I have the opportunity to buy either a new Speedlite or a ring flash. I do mostly portrait work along with apparel catalog stuff. I also do product work. I do both studio and outdoor set-ups. I currently have one 580 EXII. My question is, which would give me the most mileage? I could use another Speedlite, but the ring flash is so tantalizing. What does everyone use their ring flashes for, primarily? Love to hear your thoughts!