Arbaz, u r in a same pit,i have been in to.
I think i copletely understand your question.I used to have I30 and u are right it has a seperate control track,wich i think
is as important as a heart of a man.But yamaha would never understand it!!!
I have both the Kn6500 and psr2100.However
my 6500 does the job which u require even
more powerfuly and easily than i30.U can
alter anything in real time and step.
Thechincs give u separate tracks for cotrols
and for chords. It is as easy as 1 2 3...

On the contrary psr2100 or 2000 does not
give u real time changes unless a mirical happens.u have to finish your job using step
rec.Wait... u can alter chords in real time
using punch in and out function,say,u have
made an error recording chords in a certain
meaure or meaures use give it punch values
and u r done.In this way may be u can change
the other controls I will check my 2100
tomorrow cus now its 3AM.I think this will
work for u.