bought a new De Graaf about a month ago. Double axle 2000/4 ADJ model for Humber 7.5 with Merc 175 (similar I guess to yours in size/weight).
Very pleased with it. Tows well (Penzance and back!), only a couple of launches so far but works well. Double speed winch, hitch lock built in but lock barrel extra, single handed manouevring and hitch up is not hard, hitch has hold open switch to engage ball when you drop on.
Spare wheel, bearing buddies were also extra. Trailer is registered in own right so issued with a VIN (vehicle ID number like a car). Not sure what benefits this gives but easier to trace I guess as number plated and etched in various places.
Two banks of hull rollers and one of keel rollers. Those, winch post and hitch length are all adjustable with 17 & 19mm sockets.
Lighting bar and cable included. Lighting bar posts slide inside chasis member and add at least 1.5m.
If you need more info then PM.