Humidity range will effect how you need to store them. It does make sense that if you are storing them with just newspaper that a higher degree of humidity would help keep them from drying out. And I think that storing in whole clumps makes a difference there too.
Because I divide in the fall, and winters here are usually quite dry, I wrap all of mine individually in saran wrap. The saran wrap method works great IF you have dry winters, and you make sure not to wrap them when they are still wet. After I divided mine this year, I sorted the different types into paper lunch bags, and let them sit in those for a couple of weeks before wrapping them. It the bags allowed them to dry a bit, while holding the humidity enough to keep them from shriveling at all.
There are so many combinations of storage mediums, temperature and humidity that everyone really has to figure it out for them selves as to what will work best in their environment - you don't always have control over humidity, and many people don't have a 40-50 degree area to keep them.
If you find yours are drying out - then a damper environment is going to help, if they are getting moldy, then the opposite.
I have also read that some types of dahlias are super easy to store and will be fine practically no mater what you do, while others are almost impossible and prone to rot. - there is a genetic factor. Swan Island really specializes in easy to store tubers. They deal in such bulk they don't have the time to mess with anything that needs special care, so they don't grow them.
