i have had my utes leafs reset two inches with two inch blocks and the car handles really well, the ride is a bit rough but i think that could be due more to the 19 inch wheels, i have towed a car on a car trailer with my ute and it handled it fine and not the rear suspension didnt sag at all, a mate of mine has his leaf springs in his xh set nearly flat with no blocks and it sits nearly the same height as my ute and it handles really well too. 1800 is way too much for restet leafs, you should not be paying more than 400 to get it done. go to the white line website and have a look at the xf project and that may give you some ideas on what to do
www.whiteline.com.au go to products then suspension kits then kit for your car on the right had side then ford then then project xf part 3, hope this helps