A Kei and Makoto duet would rock my face off! Just like that Yuki and Makoto duet. Always one of my favorite performances.
And you know, even if the arranger gives them their lines, I'm sure Tsunku has some say in it. First off, he's
Tsunku. I mean, they don't ALWAYS have the same arranger, but yet the same girls always get (or don't get) lines.
And as for getting to hear Makoto sing... I really enjoyed the concert at the end of Ribbon no Kishi. It was lame she never got to show off until she graduated, yes... but still nice to hear. And she'll come back with another chance to prove herself.