If the humidity and temps can be maintained adequately in the still-air I've read that it is better to hatch in a still-air. The mentality is that the chicks don't have a breeze blowing on them, that they will stay more moist during the pipping/hatching stage, and thus the membranes won't be as subject to drying out quickly during hatching. They will probably take longer to "fluff out"/dry in a still air but they'll be warm and the chance of shrinkwrapping is lower...there's really no downside, that I see, to hatching in a still-air as long as the humidity and temps are maintained.
I don't have experience in this, and what I've written is all "heresay", but I've read this from several knowledgeable people. This spring I intend to incubate in a forced-air incubator and then move the eggs to a still-air for "lock down" and hatching.
Best wishes,
Ed