Happy times! You are deciding between two really good pianos!
The GB1k is a very nice grand piano suitable for smaller rooms like in a home, and the U1 is a very good upright piano (I own one myself and I am super pleased).
Both are very good pianos, but you have to make this decision yourself depending on your space, needs and economy. And of course...a grand is a grand...:)
I have written some articles about how to chose the most suitable piano:
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