Compare the specs. The Sport II has a 1:9" twist, which is as fast as I want to go. The gun you linked to has a 1:7", which I did not want.
For others asking why not the M&P-15 Optics Ready, it has an M4 profile barrel, which I do not want. I wanted the barrel profile on the Sport II.
And, while the Optics Ready carbine has a railed gas block, it lacks a folding rear sight. I don't see where this is worth the price difference, which exceeds what a railed gas block costs, and the gap is even more if you add the price of a folding rear sight, which I did want.
I did not want the free floating forend models either. They're even more money.
And, I wanted CAR length forend furniture, not mid-length.
The replacement furniture does cost money, but in my case I swapped with another gun.
Eventually a railed block with a folding sight or a combo block/folding sight will replace the A2 sight. But again, from a cost standpoint, it's still cheaper than getting the Optics Ready model. And the one linked to above does not have a railed block, just a smooth low profile.
So I think even when modifying it, you still get a lot of bang for your buck with a Sport II.
