Aye mine turned up this morning too :xgrin:
Think the paint flaking is just due to it being quickly assembled after painting, so there's some flaking from the contact points of the rail.
Fitting wise it's only 6 bolts to change the seat onto the rail, then 4 to bolt the whole thing back in.
Though you may need to disconnect the battery if the pre-tensioners has to be disconnected so you can fit it to the new rail.
I haven't actually put it in yet, so not sure... I'm not sure if you can just swap it over, or if the cable has to be disconnected (think there is a plug) then pulled through the old rail first.