Not any harder or hotter then reading a pressed DVD. Reading recordable media are more difficult to read at high speed then pressed disks because of lower reflectivity and higher jitter/noise. So to be conserative, benq set the drive for 8 speed reading.
However, if you use high quality disks, and weed out disks that have not burnt well, you should have no problem reading DVD's at 16speed with the benq drive because its high speed optical stability is quite good. The benq will need to slow down towards the end of lower quality disks, but it shouldn't be a large problem.