Not much, Both aspen and paper towel do a terrible job of holding humidity - my recommendation, mix in some sphagnum moss with the aspen to keep the humidity up.
It also depends on the reason your changing, if it's for humidity or ease or budget or whatever the case may be. So I'll ask what is the reason you're changing, that way you get the best advice possible.
Aspen will dry out only about 20% slower than paper towels so you're really not doing yourself any favors. I use a cypress mulch bought from home depot. It's untreated, undyed, and works well for me. I even bought some eco-earth to sprinkle in with it but I haven't needed it yet.
It also depends on the reason your changing, if it's for humidity or ease or budget or whatever the case may be. So I'll ask what is the reason you're changing, that way you get the best advice possible.
Well it was just a thought but I wanted to ask b4 I did, just get others opinions on it