I attended a Mark Citret workshop a while ago, and he makes it a practice to pre-soak all of his tray developed 4x5 film for 5 minutes in a weak photoflo solution before putting the sheets in the developer. He has excellent negatives (and prints!!) with no signs of problems. I did the same while in the workshop and did not have any uneven development problems. I'm guessing it all depends on your particular habits and local water conditions. Heck, I even hear that some people get good negs from PMK. If you can do that, then photo-flo should be a cake-walk!
P.S. Mark's url is www.mcitret.com He is an excellent photographer, teacher and all round nice guy.