I bought and did some of Womble's Sheep tests on an Aopen DUW1616L Pro-31 drive.
It had no problems reading sd2old.dat, sd251.dat and sd290.dat. No problems with sheep3.dat from sheep_3_audio.bat (530MB) also.
It couldn't read bad.dat or sheep3.dat (470MB) from sheep_3.bat though.
I can't speak for the 1608 but it looks like the 1616 is a 2.5 sheep drive...