I don't think I've posted this, elsewhere, but I used 1453's back in 2014 right when I found out they'd fit my Outback (it's now at Legacy height). With a stiffer front spring, they never provided enough dampening at any setting up to max. The 1055's in the back had no problem with the same 300lb/in rate and I run them well below maximum. The 1453's started to leak and lose damping a while back and since Koni doesn't certify 1453's for the Outback, my warranty was denied (they now require a valid copy of registration in addition to the receipt). I bought a pair of 1447's and swapped them in and their damping is significantly higher and better matched with the 1055's for my rates. I'm sure it's on this site or in the thread elsewhere, but Koni's published data is:
8610 1453sport
Tested at .33m/sec (13in/sec)
Compression – 900Nm, Rebound 1150Nm
Tested at .13m/sec (5in/sec)
Compression – 650m, Rebound 850Nm
8610 1447Sport
Tested at .33m/sec
Compression – 1100Nm, Rebound 1700Nm
Tested at .13m/sec
Compression – 850m, Rebound 900Nm
If you're a suspension tuner you know those numbers border on useless for knowing how the shocks will perform, but they're definitely stiffer at high speed and in my opinion they're clearly stiffer at low speed, as well. I have no idea if they might be more digressive and assume their curves are roughly the same shape. In summary, having an extra fraction of an inch of extension is a very good thing and supports GTeaser's thesis to prefer the 1453s. However, the damping is very significantly "sportier" on the 1447s if that is something you are interested in and for people lowering with higher rates I strongly recommend them. Since they're OE-fit Konis they are definitely still very smooth and not harsh.