I just upgraded the roast monitoring hardware and software for my homebuilt hybrid 1kg. roaster. The system was designed and built by a group of homeroasters. TC4 It is a Arduino based hardware system. There are a variety of software applications depending on roaster design and needs. 

I have a separate 16x4 lcd display that shows live, time, BT, ET, BT RoR (delta BT,degrees rise/min.) and the voltage output of the variac to the heating element. The system also graphs on a PC with usb and saves csv. data files.

The live RoR shows real detail of the speed of progression of the roast. Much more detail than can be seen with a BT curve.

Below is an example of a screenshot(see attachments). The roast was 420grams of Ethiopian DP roasted to the doorstep of second crack with an extended finish for a espresso blend component.

I still need to mount the hardware in a control box.