Alienware is not op. Just go to the Dell website and make a build. Then go to another manufacturer and make the same build. Voila, now you'll know that they're not op.
I have an M17xR4 and it runs GREAT. I did some comparison shopping and it was about the same as everyone else.
I looked at the laptop in the link and it is almost identical to mine. I paid only 2000 USD form Alienware, I have the 7970m ATI card but I bought this for gaming and CAD. The 7970m outperforms the 680m in CAD applications, it scored twice as high on some CAD benchmarks while it only scored marginally lower on most games and higher on others when compared to the 680m. Unless you're planning on 3dvision I'd go ATI. Nvidia just doesn't offer enough of a performance increase over the ATI card this time around. I have used nvidia for the last 6 years but this time around I could not justify spending the extra dough for such a small performance incease on games and less performance on CAD applications.
That does look like a nice laptop and it is priced about the same as Alienware so it really comes down to your choice. The only benefit Alienware offers is the M18xR2, otherwise price and performance appear to be about the same.
After a closer look, the only difference between that one and mine would be the screens refresh rate, mine is lower, and the max memory supported, mine will support 64GB instead of 32GB. Everything else, down to the wireless nic, is the same. I have the bigfoot killer 3x3 mimo nic and it gives me a consistent latency of between 29ms and 79ms, depending onthe game.