The A400 Xplor is the replacement for the 39X series of guns.
The main difference between a field gun and a dedicated trap gun will be in the stock design. BigJimP can tell you about the parallel stock fit, etc. that trap guns utilize. This can work well if you're shooting with a premounted gun. Typically, in the field, you're not premounting a gun, so the lower comb tends to aid in that aspect.
Most trap guns are set to shoot a higher POI than your POA. This allows you to "float" the bird when shooting, as trap targets are shot on the rise.
Their UGB Excel was designed for International situations where folks like a semi, but safety concerns dictated a break open gun - thus their hybrid. I was able to shoot one a while ago when a writer was doing a field test - it is soft shooting - one of the softest shooting I have ever used; but it isn't cheap.
If you like the Urika, get it fitted to you and go smoke some targets. Beretta's seem to be THE choice for semi's when it comes to clay targets.