Figured I should add an update.
After grooving and siping my tires, I have noticed a definate increase in snow traction. A couple weeks before I did this, I went snow wheeling and seemed to struggle following another jeep through snow. Last weekend, went snow wheeling again, following the same jeep, and noticed in places he struggled I rolled through easily. Now, both times, the other jeep was breaking trail, and I was either directly behind or two rigs behind. But I would say snow conditions were probly similar.
The other difference I have noticed is at the first stop sign on my street on the way to work, or well, any place. Stopping at this stop sign means your are stopping at a slight uphill. Before grooving and siping, in 2wd on a plowed but snow covered road, I would just sit there and spin my rear tires until I put it in 4wd. I mean I could sit there all day and go nowhere. After siping and groving, the tires still spin, but definately grab and slowly work their way up the hill.
I've also noticed that in hard stops on snow coverd roads I stop in shorter distances.
One thing I did notice that didn't change was road noise. I did a lot of reading before I did this (at least 30mins), and some sources said that they experienced a decrease in road noise after grooving. I didn't see this, but I will say it may be because I didn't groove the lugs in half. Meaning for each lug I grooved, there was a big side and a little side, so that the "slap" that makes the tire noise didn't really disapear.
All in all, I'm pretty happy I did this. I'm even happier that I only grooved to about half the depth of my lugs, so in a year or two I will get to try again with a more complex pattern. Definately worth a shot for those interested in getting more winter traction out of their MTs/