Are chains mandatory? Prior to our acquisition of a JD 2320, we blew our asphalt driveway with a Simplicity Broadmoor w/42" blower. I needed chains and plenty of weight for the Simplicity and still were plenty of times I spun going up the driveway. With the 2320 (R4's) in 4WD, I never ran into issues not being able to make it up the driveway.
As Kenny stated, the R4's can be slick. I noticed this is true if there isn't enough snow for it to get traction with. In fact, I used our 2320 to blow a path over our grass to get back to the horses. I was careful to keep the blower 2-3 inches above the grass and used our BB (@ 600lbs). As you can see from the pics, the drifts I went through were higher than the blower itself. I was a bit nervous about how the grass would come through in spring but it was fine. Granted I did not have to run over this trail but once a month and in between time, there was time for it to blow in with new snow.
Btw..the pitch of our drive is approx 9 - 10 degrees (or 2:12).
But your post also drives at a long debated question regarding R4's versus turf. Personally I have found the R4's to be good fit for my applications. Regardless which style you choose, I would hold off on getting the chains until you have had a chance to try the 1026r with 4WD. As a fellow owner of an asphalt driveway, I know what chains can do to it and/or concrete.
But most of all, congrats on moving forward with the 1026r. Have fun with it and hopefully the wait isn't too long.