Well, I took it out for work today! And, I must say, it performed very well.
Worked in the outdoors today with the SP3. Handwritten notes, quick look ups for information, email etc. while being connected to the local WIFI network, manipulating Office documents, more handwritten notes...etc. All this, mind you, is taking place with us sitting on the grass, under the protective shade of a clump of trees and under a sky where the sun played hide-n-seek behind the clouds and which was aired by a brisk summer breeze!
And, yes, the SP3 performed brilliantly. Did not heat up (though I would not have been able to hear the fans if they had come on), did not lose its WIFI connection, pen worked fine in conjunction with OneNote and with DrawBoard PDF (handwriting notes to text etc.).
One important issue though - there is too much screen glare and if you are forced to consistently work outdoors, then you are going to have to turn up the brightness of the screen and burn your battery.
Edit: Btw, I am running the i5 4GB, 128GB everything updated version - everything just as it was out of the box in terms of system settings.