As an avionics tech there is nothing more frustrating than a system designed on precedent and theory, test flown a few times then mass produced. I do not know how many times I have had a bonehead engineer on the phone with nothing better to say than "I do not understand why it is doing that"! They use an operator to test and help them wring out the problems with the crap system they designed.
Ok rant over... It pleases me to see Honeywell putting the extra effort into R&D, they have a good reputation. This aircraft is probably primarily used for engine development, you can not completely simulate environmental conditions to test an engine in a test cell.
GE and Boeing both operate a 747 for this purpose, the GENx engine for the 777x is the last I have heard of undergoing test flight.