I checked the Yamaha spec and they appear to use 2.5” drives as used in laptop computers, the most common speed at present being 5400rpm, (Although in 12 months or so it will probably be 7200rpm) and are used to give a balance between battery life and performance, As you will be running the drive off a mains feed you can go for as fast a drive as you like.
The big advantage for a faster drive is the significant decrease in the time taken to read and write to the drive. (The seek speed has no relevance to spin speed, in fact some slower drives have a faster seek time then some faster drives)
Hope this helps in your decision.

Bill