I use the fully configured P1 with P2000. But with the (very nice) 2K Screen.
Solidworks, Composer and all kind of office use.
In the office with a 4k Eizo, everything works and looks perfect.
No loud noise from the fans and i dont feel it gets hotter then the P71. (on the hands)
I had before the P71 with P5000, don't feel much downgrade but much much lighter for travel.
The 4k 17" screen was with solidworks problematical. I worked most time with 2k, that was fine.
The P71 is a nice machine, no doubt - i sold it to someone who works mostly stationary. He is happy.
And i am very happy with my P1
By the way, the lenovo docking from P71 was always flawless, the smaller dock compatible for P1 doesn't work steadily, i plug the 4 connectors manual - maybe later.
I would not buy a gforce for solidworks, i have too much challenges with solidworks and my constructions, don't need make my life more hard with gforce
What is your P1 configuration? Which CPU?