I think you'll find the 96 merely shifts the frequency balance, maybe pushing the midrange more, giving the impression of more clarity but at the expense of overall finesse. This is what wma tends to do compared to mp3, and some people prefer it. But you tend to lose out in the bass and treble perhaps.
But if you rip high quality CDs the difference between 320 and 96 is pretty obvious. At 320 most people would be hard pressed to tell the difference in a blind test. I gradually replaced all my mp3s lower than 128, and encode at a minimum of 160 nowadays (depending on source) because I found even 96 not quite good enough on good material. The lame encoder is definitely the best for mp3 and easily used with the free converters.
But this is for ripping digital master CDs; for the keyboard, even though the quality is very good, you may not need exactly the same resolution, or even prefer the compression, almost as an extra effect. Quite apart from personal preferences so much depends on what you actually use to listen to the final result too.
The jukebox converter does a good job, and aac is a worthwhile format - just archive your originals so you can check out as many times as you like. For an example of 7k encoding see
http://www.synthzone.com/ubbs/Forum25/HTML/000911.html