The GPS will handle phone calls in the same way as the TFT. However, the TFT allows you to handle the phone by using the Woderwheel rather than stretching forward to reach the screen for controlling the phone.
Also, the TFT connection allows playing media from the phone, as well as streaming of music or radio through the phone (But data cost and shortening battery duration for the phone will probably limit the enthusiasm .)
Display of speedlimit and traffic messaging may also be handled by the GPS.
I think the way TFT handles the phone is great, but it is annoying that for some reason, the TFT out of nowhere drops the stored connections, both to helmet and phone.
I do not know why that is, and it seems even more silly when you experience that pretty much anything else does not have this issue.