I wouldn't consider going without a screen protector on my iPad, but for a completely different reason from any others that have been stated. Twice in the past 6 months my iPad has been dropped (not by me), shattering the screen. Both times I was traveling and at least 3-4 days out from an Apple store or repair center. Both times, however, the shattered screens were held intact and in place by the screen protectors, enabling me to continue using my iPad until I could have it replaced or repaired. Yeah, it wasn't pretty to look at either time, but it worked and since I use my iPad for work the screen protectors were life savers.
All that being said, I've tried a bunch of screen protectors and most of them suck. The best I've found by far so far has been the PS Crystal. I did just order the Nushield DayVue anti-reflective (NOT matte anti-glare) to try, however, so we'll see how that compares.