You'll get every opinion here. I have both; my Sport is one of the first, with the 1:8, 5R barrel. I took it out last weekend for the first time in a long time. I'd forgotten just how good it works. It's my opinion that the barrel is superior to the chrome lined barrel on my Colt. With a red dot on there though, you're never going to know the difference. In my case, there's simply no need for a forward assist or a dust cover. I shoot my rifles and am not just an internet commando. I've never needed either of those. I have other ARs with those items and they've never been used. In point of fact, I prefer the looks of a receiver with a slick side anyway. I would be just as happy picking up a Sport if I'm in need of an AR, as any other AR of any brand.
With all that said, it's just a matter of whether you want that barrel or not. I've found the 5R rifling to be a bit easier to clean, with the more gradual angle of the lands, but that's pretty subjective. Others also call the Sport an "entry level" AR... I view that as an error in terminology. It's simply a rifle with less accessories on it when you buy it. It still says "M&P" on it. It still functions the same and shoots the same caliber bullet.
Get what you want, get what you like, and don't bother thinking much about what the guy on the next shooting bench is thinking, because he really doesn't care much about what rifle you're shooting.
Just my take on it.