Surface 3 with lte vs Surface pro 3 with usb lte

We currently use iPads with lte for onsite issue documentation. We need Internet and gps for location of inspection and connection to our database. I would like to switch to surfaces as they seem to be a more useful machine for work environments. Should I just replace my iPad with a surface 3 or should I attempt to replace my iPad and laptop with a surface pro 3 with a usb type lte connection? Any thoughts are appreciated.

I run typical office programs but use autocad for drawing review and open large pdf documents frequently.