You mean Lumia 950XL, correct? There is no 940 device.
If you meant the 950XL, I think it is a much better device than the 930. I would personally wait until March till all the firmware/WM10 software issues are sorted out.
wow, if you can get a 930 cheaply, you should do it. Great phone. Thicker and heavier than a 640, but everything about it is so much of an improvement over the 640 that you won't be sorry.