I haven't, but...
Bought a refurbished (apparently.. but that's another story) from a seller but one of the many problems with it was the transferbox sump leaked terribly. About 600ml over 3 days.
Bought a Roamer Drive billet sump plate and fitted up with the new (supplied) gasket and bolts (also supplied) that replace the studs.
End result is not even a weep, let alone a leak. Can definitely recommend.
I paid approx. £100.