There may actually be a valid reason for copying it to your hard drive first. Dvd burns data very fast, especially with higher speed burns. Even going directlly from an internal hard drive, if the hard drive is too fragmented, it can cause problems. You might want to try benchmarking how fast you can pull data from the terra station. Also, are others using the tera station at the same time as you? If so, they could crash your burn. Burning with slower speed disks might ease the need for fast data transfer a little, but slower speed disks are getting harder to find (good ones anyway) and that defeats the purpose of saving time.
Thats why it's not recomended to burn dvd on the fly. It's not that you cannot do it, its that there are lots of things that can cause a momentary slowdown in the data flow that can hurt the burn quality or crash the burn.
sisoft Sandra (just google it) might be able benchmark the network speed (not sure as I'm not to farmiliar with networks). You need about 24MBps and have to be able to sustain it with out slowdowns for 16x burning if I am not mistaken.