Physically they'll fit but the upright on the rear seat sits at a slightly steeper angle in the saloon. When fitted in an avant it's not noticeable from inside the cabin but there's a slight taper where the rear of the seats meet the side panels of the boot space instead of a parallel gap, nothing much to worry about tho. I fitted the lower brackets that they pivot on from the saloon as they are also different from saloon to avant but it didn't make much difference.
The load cover is a slight issue as the saloon seats don't have the recessed metal plates sunk into them for the cover mounts. I just attached them directly with self tapers straight to the backs of the seats, it was quite tricky measuring and marking to get them in the right place. Obviously the self tapers aren't as good a fixing as the original plates so I fitted little rubber stops to the side panels of the boot space so the load liner sat on them too to take some weight off the screws. Others have stripped down the seats and swapped over the metal backs but that was a bit too drastic for me, 2+years and it's caused me no issues.