£5700 difference,not as bad as you think really and the reason you don't see any 722s kicking about.Hmmm I wonder how many £10's there are between the price of a new 720 and a 724?
Only difference besides stickers is heavy duty bearings in the transmission,won't be £500s worth.
Years ago I did my research on the difference in a 6330 and 6430 deere,besides stickers the only difference was rear hub flange 275mm pcd on a 6430.
One thing I'd agree on is never map the top tractor in the range they're usually top of the tree anyway.