I've got three identical boxes (6016T-6RFT+), two have the IPMII F/W 2.03, the last has the older 1.32. The two newer boxes take approximately 15-20 seconds to start printing data when running "sdt", and then almost half a second before printing each line of data. The box running 1.32 takes approximately 0.5-1 second to start printing data, and prints it all immediately.
All boxes are running Supero Doctor II - Linux version 2.78(101215).
Please upgrade the firmware to v2.21 that will be released later, or contact Tech Support at support@supermicro.com for the beta firmware that reduces the delay.