It would be good to weigh it. Ideally at all four corners, but the CAT scales, common at truck stops, give only three axle weights. They call them Steer, Drive, and Trailer. With an RV it would be Front, Rear, and Toad/Trailer. The coach's' wheelbase will have a lot to do with axle loading. Depending on wheelbase, you might not see any benefit to those extra 400# of front axle load rating. I don't have the numbers to prove it, but from what I see and read, there are more Class C's with overloaded rear axles and underloaded front axles than the opposite.
Also, if I had to guess, the coach will weigh out heavier, not lighter, than that placard, and you'll end up feeling worse than better about the Jambo.
Tom's right about mfr pushing the limits, buyer following their numbers, or not paying attention. Our Jayco is entry level by any definition. 31-ft with no slides and very Spartan interior trim. Our Axle Weights are in the high 90% ranges, Front and Rear. I think it's because they used a steel floor frame system and newer ones have aluminum. Looking at it, you'd never believe it's so heavy. And the placard says it isn't.