Hi. I don't have any experience with worm towers, but I noticed no one has responded to you. I've only ever used the cheapo plastic storage containers and I get the impression most of the people on this forum also make their own worm bins, rather than going the store-bought route.
I will say that I occassionally long for a tower system to see if it helped with harvesting (i.e., separating the worms from the vermicompost so it can be used without sacrificing the worms). In my admittedly limited experience, none of the various methods for harvesting seem to work very well.
So, some sort of tower system might help. But then again, the worms might just stay down there in the bottom level and never move up. I don't know.
I bought a worm farm from the Worm Dr. and I like it. It started off slow because my worms spent the night in my mailbox and it killed half of them. Then I overfed it and it was too wet, etc. I've had it for almost two years now and it is working well, now. I keep it in my unheated cellar. The cellar space is kept from freezing because of the furnace, so it keeps the worms at the right temp. I wish I could keep it closer to the kitchen, but I only feed it once every two weeks or so. I haven't harvested alot of worm castings, as I've been too cheap to buy more worms, and my worms just weren't numerous enough to get the job done. Now I seem to have alot more worms, all ages, and things are picking up. I think my two biggest hurdles were not having enough worms, and not following the directions closely. I have alot of bugs in the bins so I am glad it's not in my house. I still struggle with it being too wet or dry, but the worms don't really seem to care what I do to them.