The whole reason for tanks is apparently just for aesthetic. It's overall a bit more trouble and more expensive to set up, and tubs are just the easier way to go. There aren't really any concerns, I suppose! Regarding light, I still haven't found the answer to that either, so hopefully someone knows :o

And I'm sorry to hijack the thread, but I also have a related question... How many holes in the tub is appropriate for air circulation? I've seen ten holes to twenty holes, and not sure which is good while still retaining humidity...