Today I weighted up the plane to 5kg flying weight (bigger battery). Much better tracking and not as floaty. It also sinks nicely on approach as the extra inertia doesn't let it balloon when a wind gust hits it. I'm thinking it could still be a bit better, so I will try it with a flying weight of 5.5kg next time.
I'll be sure to grease the landing though as I don't want to bust the gear.