Wool dryer balls

I didn't even know about wool dryer balls until the other night.  Apparently, they're supposed to replace fabric softener sheets in the dryer, speed up drying time, and fluff up your laundry.  They might even reduce static cling unless you live in a dry climate (like Las Vegas!) and don't mix synthetic and natural fibers.  There are a few sellers on Etsy that offer them.  I was looking to join a swap on Craftster.org and kept seeing these pop up in the swap packages.  My curiosity was piqued.  I got out a skein of good old Red Heart acrylic for the core and 100% wool for the outer balls and started winding.  I wrapped the core to 7" in diameter, cut that yarn and then started winding the 100% wool until each ball was 9" in diameter.  I then took the yarn end, attached a yarn needle and buried the end deep inside the ball.  I managed to get 6 balls out of my wool.  I put the first ball into the toe of a knee high stocking and tied a knot close to the ball.  I continued like this until I got all 6 balls into that stocking.  They went into the washer with a load of laundry on a hot/cold cycle with some detergent.  It took 3 cycles for them to felt to my satisfaction but now the yarn is completely felted and won't unravel at all. 

How are they in action?  I think they're neat!  I think they've cut my drying time by 20 minutes.  They made my towels and blanket fluffy.  They may even help get wrinkles out but I'll have to test this theory some more.  I don't know if I'm 100% sold on not using fabric softener.  I miss the smell.  I did try one load of clothes without fabric softener and it came out just fine.  I also read that you can add essential oil to the balls and I may try that sometime.  I know for sure that I'll be making these as Christmas gifts!