If you are doing a cafe seat, the airbox might get in the way. On the 77-78 (what I know), the airbox cover comes up and the intake scoops air from the side over the frame rail and under the seat. Just another reason why I initially went to pod filters. Eventually I tired of the very uncomfortable seating position and clip-ons, and I returned to the stock seat and Euro bars. In stock form, the CB550 is one of the most comfortable bikes I've ever ridden. I kept the pods, though, as I really like the look and I enjoy the boost in performance.
Also, I can't speak for all pod filter users. I only know that MY bike is harder to start in the winter with my pods, exhaust and jetting. While it runs beautifully under all other conditions, it is certainly possible that cold starting is a tuning issue on my part. It would be helpful to hear from others on what their experience has been with pods and cold starts on cold days.
I also remember back when I was a kid and had my 1970 Mustang, it had an open air cleaner, too. It didn't have trouble getting it to start, but it took forever (maybe 5 minutes) to warm up and run reliably. Again, in my opinion, it was worth it to have the additional performance from the less restrictive air cleaner.