It won't be "significantly" worse, but for the same price you could get 2 Windows laptops. Aside from the Retina display and the 650M GPU there is little that would make a MBP stand out. And most "serious" CAD programs run on Windows only, too, just FYI.
If money is an issue, then it's much better to spend some of the money you would have spent on the rMBP on a Windows laptop with more RAM in it. The base MBP has 8 GB of memory, which is low for the types of programs you are looking at running. If you can get a good laptop with 16 GB of memory for the price - buy it. Memory will make a significant performance improvement. Also, for AE, try to get a laptop with an nVidia graphics chipset. AMD is OK, but you will get much better performance out of the nVidia cards.
I have a decked out MacBook Pro Retina and it works very well for all CS6 apps. It's actually faster by a bunch than I thought a laptop could be. I have several personal reasons for going Mac. They are my personal preferences and experience for reliability, stability, and customer service. I'm not married to OSX. If a better system for me was available I'd be using it. The for me is the critical part of that statement.
The biggest advantage of Mac computers is that there is very little chance that the components have not been fully tested and integrated. The QA/QC in all Mac hardware is some of the best in the world. Every Mac I've ever owned has been virtually trouble free mechanically and outlasted every windows machine I've ever owned. Apple does make mistakes and fouls things up, but the chance that you are going to end up with a machine that just works and runs and runs is much higher than anything built from the variety of components available on Windows machines.
Now my comments on windows machines. There are more manufacturers that I can count. There are more hardware combinations that I can imagine. Some manufactures produce excellent products. Some are just junk. Some last a very long time. Some breakdown all the time. If you were to go Windows make sure you check out the reputation and the warranty of the company building your machine. I've only owned one really high end Windows machine from a high end manufacturer. It ran just fine for about a year and a half before it needed some major component replacements. The warranty was out, there was no extended warranty available from that manufacturer, so the repairs cost me about 1/3 of the purchase price. If I'd gone with a company with a better service policy I would have saved a boatload of cash in the long run. Every other windows box that I've owned has been built from scratch or purchased in a shoe string. It took a fair amount of monthly maintenance to keep them running well.
You mentioned CAD... Audocad on the Mac side is really crippled. My associate has the full Autocad Civil Engineering package running on his MacBook Pro Retina under Parallels. It's working fine. It's one of the largest and most complex CAD packages available. It actually works better on the Mac than it does on his HP laptop and the Mac batteries last a lot longer. The HP laptop cost about half what the MBPro did. It's about 6 months older. It's not as loaded. If you were to replace the HD in the HP laptop with the same capacity SSD that is in the MBPro and bump the memory up to 16GB the HP would still be less expensive than the MBPro by about 18%. The HP is plastic and aluminum with a display screen that's very sensitive to scratches and damage by pressure. The HP is not compatible with CS6's ray traced rendering or Mercury playback for PPro. There is an HP model that is though.
You be the judge. Balance your budget and the software requirements with the expectations of reliability, service, customer service, and resale value and make your choice.
Hello, sir! Thanks for your very informative answer
I just went to Autodesk's website about AutoCAD 2013 and it says it's Mac compatible, so is this a good thing? Or is Windows still recommended for CAD?
Also, The rMBP has a great battery life! But is that the only laptop that has the legendary 7 hours?
(Just trying to look for alternatives , But I'm heading for a decision of getting the rMBP )
My MBP has twice the battery life of the other (major brand windows) laptops I'm also using. I think it's the best bat life available today. May not be the top tomorrow.
I'd check with AutoDesk about AutoCad and make sure they know what kind of work you'll be doing. The versions my associate uses in his daily work has far more capabilities on the Windows side, but then again, He's running Windows on his MBPR...