AlGaN/GaN HFETs have been fabricated on epitaxial wafers delivered from different vendors using 250 nm GaN HEMT T-gate technology. The specified epitaxial design of all wafers has been the same, the wafers have been procured from 9 vendors world wide. Non-destructive material characterizations before device fabrication and extensive characterization of the final devices enable correlations of device performances with epi-material quality. Furthermore, preliminary reliability evaluations were performed on packaged devices. Devices from the best wafers in the contest demonstrated high reliability. More than 3000 hours device lifetime has been obtained on devices operated at 50 V and high channel temperature of 320°C.