Hi dillydally!
Thanks for your compliment!
Indeed it's hall sensor (you can have more info about them in the pdf specs on Smolka Nidec website)
but they are not usable for absolut positionning like potentiometer.
The inbuilt hall sensor can give you average speed (one tick per turn of motor) but no positionning sadly...
About the motors you linked, they have half torque and twice price compared to Smolka... not a good deal
yours
Mat