To answer your questions briefly and in order:
1. using 'sport' auto mode more often than selecting, but probably will increase use later
2. So far, using it for experimenting, think it might be useful in sporty driving conditions or in bad road conditions but not 100% sure.
3. Its nice and gives added choices.
My opinion:
I feel that the biggest benefit to the transmission is the 'sport' mode. On the 2.5i (regular) when you move the shift lever to the left of the "D," but you don't shift the gears yourself, you get slightly delayed shifts which delay even more under heavy throttle. It makes a much bigger difference than some systems I have seen on certain Swedish cars of the past. This mode is one of the biggest reasons I thought the OB drove nicer than the Forester (both 08) when I tested them.
Using the sport mode gives the car a lot more zip. Staying under the 4000 RPM mark for the first 1000 miles was more challenging when in this mode.
I've never been a fan of entering a new gear (especially when downshifting) with no control over how fast the gear engages (read: no clutch). I always thought that not having control over that aspect put the manual-shift-automatic at a disadvantage around turns compared to a manual or a regular automatic (sudden engine break causes a feeling of oversteer at a speed where neutral power would feel more, well, neutral).
I'm probably a bit off base here but that's what it felt like when I used the sport shift on my Dad's old type S Acura CL. There must be a reason Porsche was using it on the 911 though, I just never really understood how it could be better than a manual. I never really understood how that could even be true in F1 but I suppose it is since they use a 'clutchless manual' for racing (
AFAIK).
All of that having been said, I will add that when I have used it, it transitions pretty smoothly even on downshifts. I'll probably start using it more as I learn its capabilities and limitations but with the NA 4cyl, I'm just looking to add a bit more fun, not tear up a WRC race. It is NOT a substitute to the fun that a manual provides but it does have all of the advantages of an automatic and the extra choices make it more fun to drive than a 'normal' automatic, especially the 'sport' mode.
It also allows you to use the manual select to start off in 2nd gear but I think with AWD, this isn't such a big advantage. Without a "2" or "L" selector, it might also be useful for going downhill offroad or on slick surfaces but I think that even 1st might be geared a little high for doing that at really slow speeds, might just have to trust the ABS (yikes!). It also could be that selecting "1" in the manual mode forces the 50/50 front/rear power bias but I haven't tried that.