Had a twin axle degraff. Very well built, although mine wasn't really ideal for a RIB. It has some sort of cruiser on it before I had it which is presumably what it was designed for. It had keel rollers as well as side rollers. The keel rollers made recovering the boat a nightmare - you had to get the keel right on the rear roller (which was underwater) otherwise the boat wouldn't sit properly. I was tempted to cut the keel rollers off but then sold it and replaced it with one without keel rollers. Without them its much easier to recover - you point the boat in the direction of the trailer and drive on. I've just bought a boat with a DeGraff which I don't think has keel rollers - we'll see how I get on!
Apart from that they have a pretty good rep