B1151 looks as good as other Robot series mechs and it's stability is somewhere in-between B1120 and B1153. Sluban was always around the better manufacturers, though never among "the best" ones. However, their licensed (for Asia markets) Pacific Rim series (2018) was a huge quality jump for the company. I guess after the initial success (followed also by the success of their Super Mecha Champions series in 2021) it was decided to get around the licensing by slightly transforming their mechs and that's how the "Robot" series was born in 2022.