Yup not only does it work there but it also works on the choas planes. Takes forever though and you have to watch for the pop-ups as you defeat the banshies. Another suggestion is to take an SS and FoC Necro. They make some areas go much faster and allow you to clear all of UW including every quest with the exception of the 4 horsemen. Taking on allthe webdryders is fun but a little nerve racking.
I've also found that the Earth Ele/Necro dual is quite successful to clear most of the UW - having a prot monk with SB is pretty much essential though. If you can communicate well, Terrorwebs are no issue at all (with SB and Obs Flesh).
