I'd go with th MO. The 625 is a toy compared to the MO8.
The Mo8 also cost twice as much. the Mo6 cost 999, only a little more than the 625.
The Mo8 will have weighted keys which are important to your development as a Master Pianist. It will also have better sounds, be more durable and have more profesional features.
I suggest you hit up Sam ash or guitar center. If you cant, and you need mor help check out the websites, and consult us