Lukitoh,
If the right hand harmonizer is important to you, then the psr's (ALL of them ) are out as well as the Korg. I nevber worked with the Gem harmonizer because i don't like the way the kb sounds, and the only one that will do what you request is the Ketron line up. Terrific sounds, great styles and a harmonizer that follows the right hand WITHOUT the arranger as a trigger.

I use the PA80, but I use a Digitech harmonizer. The Ketron falls alittle short of my wish list, but you'll probably like it the best off all the choices. The Yamaha and the Kork will allow right hand triggers, but the harmonies will not sustain unless the arranger is also triggered by that hand, and the Yamaha doesn't even offer RH triggers on the arranger.
For a manual bass player, like you & I - the Ketron is the only built in harmonizer that is acceptable. The others all work best with the arranger as the "boss".
Sorry, Charlie ... in my shows, I'M the boss.