I was very surprised that Antec would design a gaming case that had a 155mm cpu cooler height limit.
It would be stupid to design such a case that did not allow installation of the vast number of good coolers in the 160mm size.
So I did some research.
Here is a review of the case which appears to have a prolimatech supermega cooler installed. No mention is made of having a cooler height fit problem. http://www.techpowerup.com/reviews/Antec/ONE/5.html
The cooler is 158.7mm high, and it certainly looks like it fits with room to spare.http://www.prolimatech.com/en/products/detail.asp?id=158&subid=427#showtab
In the newegg feedback, I see no mention of the cooler limitation as a con.
What I think is going on, is that Antec has limited the height on the assumption that a fan is installed on the side, taking up at least 25mm. No side fan is really needed, so I would ignore that limitation, at least up to 175mm or so, and buy whatever cooler you want. If it does not fit after you check things out, return the cooler in favor of a downdraft type cooler like the
Noctua NH-c14: http://www.newegg.com/Product/Product.aspx?Item=N82E16835608020
Perhaps an inquiry to Antec would clarify things.