Most MOTL and TOTL arrangers, including PSR-S910 and Tyros4, have good basic sound editing, which is perfectly usuable for those times when you want to lower/raise the attack/decay/sustain/release rate, change the brightness and harmonics etc.

This is totally fine enough for 99% of editing the average user will need.

Korg arrangers offer even more editing depth, although, I must add, I'm very content with what Yamaha gives me.

Why would someone care what someone else thought about the instrument they used on a gig?

If it does an excellent job, what difference does it make?

I know it certainly doesn't bother me.

As the late Liberace used to say, "Thank you for your very amusing review. After reading it, in fact, I laughed all the way to the bank."

Ian