The P50 is pretty impressive, especially compared to my older W540 which is a brick. We just ordered one for a new-hire on my team, and we'll probably end up replacing the W540/W541's over the next 18 months as everyone becomes due for a hardware refresh.
I switched, and it's incredible. I have 64GB of ram and a xenon processor. It's incredible. It's not as sleep as the mac, but I spend so much less time waiting.
I never have to think about "should I close down this VM/android emulator" etc. I have more RAM then I had hard drive space on my laptop in 2010.