I switched to a MBP three years ago and the machine hums along as fast as the day I got it. I use Windows on the machine all day. In the day job I run Revit, a Windows-only BIM cad platform that is incredibly resource intensive. I installed via boot camp and ported it into parallels. When working on small projects I can stay in the OSX environment and run the program in parallels. If I am in the zone on a large project I can switch to boot camp and, frankly, Windows runs better than it ever did on any of my 'true' PCs.
I have Sonar similarly installed. It's not a viable option to run it in parallels. Parallels utilizes driver translation for hardware. With my 18i20, the latency is too high and I lose access to many of the features of the interface. In boot camp, however, it runs like a champ.
Now, several others have mentioned and I'll concur: you must utilize a high end spec. In 2013, when the retina MBPs first came out, that meant I paid $3300 for a laptop. I spend most of my day running a $6,000 software suite so the cost of the hardware pales in comparison, but that's a lot of money that could go to a very powerful PC. I carry around an iPhone, two iPads and an Apple Watch, so the benefits and synergies of the apple ecosystem are worth the expense for me.
Dell's latest high end notebook (XPS17, if memory serves) is really the only Windows notebook that can hold a candle to the quality of the MacBook Pro. Perhaps not coincidentally, the machines are similarly priced.
I won't go back to a PC. Sadly, I may leave Sonar behind. It is undoubtedly the best DAW I've touched, but I need it to be a native Mac application. I've been learning Logic, and it is really good. Good enough that I can't be bothered to shut down and reload into boot camp just to use sonar when I feel inspired. Oh, and using an iPad as a controller for Logic is a stunning experience. It's everything you'd ever imagine it could be.
Reactor.