Thanks to everyone here for their insights and valuable contributions to finding a speaker alternative to the TRS-MS01 specifically designed by Yamaha for the Tyros.

After finding out the actual size/weight of the Tyros speaker system and how they attach to the kb, and then giving this subject more thought, I've come to the conclusion that the Tyros total weight including its speakers is 40 lbs, and 10 lbs lighter than the PSR9000 (50 lbs).

I'd much prefer lifting 2 much lighter units separately (Tyros KB: 27 lbs, and speaker bag: approx 13 lbs), rather than dealing with lifting a single bulky sized 50 lb keyboard. I'd estimate Tyros speaker setup time would only take a matter of seconds, especially if you permanently attach the satellite speaker mounts to the KB. Just my thoughts. What do you guys think?