Personally I have never used a Macbook or any OSX device. I have tried them out at outlets though. Most recently, I have been using a Dell Latitude E6220, which feels great to use. Most of my work I do on my desktop, it has a Phenom X6 1090t, 4 gigs Mushkin ram and a GTX580. Display quality matters a lot to me, and so far I have not been able to find a comparison between the displays on these notebooks. The higher resolution is a major plus, but if the quality of the IPS display on the Precision is really that better than the Mac, then I can look over the resolution. Also, as I said before, I am looking to use it for at the very least 5 years, so I am looking for the one that can provide better performance over that period of time.
PS: i use Ubuntu mostly for my work except for 3D modelling where I use Win7. Also, I hate Win8 cause it has many issues running older games...