Scott,
I'm not sure how much more I can say on the QY70 subject. However, before going on I have to set everyone straight on the PMA-5 matter. "You cannot play chords on the PMA-5 from a midi controller keyboard." Anyone who thinks so is wrong. I'm sorry to be so strong on this but I have been selling these for years now, and I've had to proove this to potential customers several times by actually calling Roland Corp. US and having the customers speak with a tech support person. The only thing you can play via midi keyboard is the tone generator. No chords can be played via midi. You can only record chord changes by step or realtime recording by using the supplied pencil. I hope this finally clarifies what the PMA-5 is and is not capable of doing. Also, I think I have already given my opinion on the i40m module. I love it but realize it doesn't run on batteries and so wouldn't help you on you quest. It does add the vocal harmonizer and a guitar input with guitar effects including wah, distortion, reverb, echo, etc. etc.
Now, yes, you did find the one paragraph in the QY70 that explains turning on the fingered mode enabling midi control of the chords. And yes you are correct that if you move the split point all the way up to the last key you can have a pianist mode, however, no right hand sound will be played with the fingered chords. And yes, if you split the keyboard (actually you are spliting the QY70) you will have a sound on the right hand and the chords on the left hand.
Now, I think this covers everything, and again please let me explain to all of the others who have posted replys to help you, I am a music store owner and I sell all of these products you are all using and talking about. I have a very good working knowledge of almost every product we discuss here. I am certainly no genius but I do consider myself an expert compared to many music store salespeople. I enjoy giving my support to you all and enjoy the discussions we all share on this forum.
George Kaye
Kaye's Music Scene
Reseda, California.
818-881-5566