I do not own a Grundig G4000A (internally identical to the YB-400PE) and only handled an unpowered unit in a store. This brief review is based on that experience.
I was instantly annoyed with the odd sponge-like operation of the keypad buttons. The buttons had to be pressed in a bit before the clicking sensation of the electrical connection was felt. Based on my experience with the buttons, I did not enjoy using the G4000A. Maybe this type of button helps prevent accidental usage? Anyone with a YB-400PE/G4000A is welcome to comment on what they think about the button feel. I don't know if any other review already mentions the weird feel of the buttons, but I don't recall hearing about it.
Other radios I have used (Kaito 1102, Sony ICF SW7600GR, Eton E100, Tecsun PL350) have more responsive buttons that allow for rapid entry. When listening to shortwave, I have a self-prepared broadcast schedule at hand. If I tune in and hear a weak signal, old content, or just plain boring stuff, I will move to the next available broadcast. Sometimes there are two good broadcasts on at the same time; I might frequently switch between them. Since I don't make extensive use of frequency memories (the YB-400PE/G4000A only has 40), I am continually entering direct frequencies.
The size of the G4000A, perhaps mostly to accomodate its speaker, seems too large for me given the features it has.
When I first started evaluating portable shortwave radios, the Grundig YB-400PE was a leading contender. Passport to Worldband Radio gave the YB-400PE top marks. I am glad that I ultimately chose something else, and was later able to get a feel for the G4000A without purchasing it, because I would have been disappointed.