I've used both with campden and without. When I am able to acquire cider and process/pitch the same day, I don't do anything to it, and it turns out just fine. If you pitch a proper amount of healthy brewing yeast (use one of the online pitching rate calculators) it easily overwhelms any wild yeast and/or bacteria.
There have been some years where I've not been able to pick up the cider on the day the LHBS presses it, so they sulfite it and store it in one of their walk-ins for me until I can get it. I've not noted any taste difference, fermentation difference, or other side effects of the addition, but from my experience it isn't a necessary step if you can press and pitch immediately as noted...
Packaged: 15 Minute APA, Simple Cyser '14 (Nelson Sauvin Dry Hopped!), Spiced Cider, Spur of the Moment Graff
Primary: Simple Cyser '15
Secondary: Why do I keep this line here...?
Bulk Aging: Cocobochet, Wild Cider (2014 & 2015)
Planned: Fruitcake Old Ale, Not Just for Breakfast Stout. Otherwise, so many ideas, not enough time to brew them....