I messed with a similar issue for quite some time. I wanted my system to play through my Roland/Rogers keyboard for the 'better sound'. Then along came VSC Dxi and it was as good or better.
I used various versions of midi to the computer, but not back, used a non-powered mixer and ran the keyboard direct, then via midi to the Dxi, with sounds being mixed by me, and volumes set and saved etc....

Then I migrated to the current system. My midi sounds are from the Ketron SD2 I got from PG music. Wow. I then ran the midi out of the Roland Keyboard to the computer via midi to usb cable, so I could play some of those Ketron Sounds.

So now, after spending a bit of cash I have a Bose L1 Model 2. With the Tonematch as a mixer. The keyboard goes both directly out, and via midi to the computer through to the Ketron. To make things a bit more complicated there is the issue of midi out and chained so it runs a VoiceLive box for harmonies using chord triads on ch5 (midi).

As far as drums I have almost no midi drums or no midi drums it's all RealDrums. Suits my genre.

Of course all learning is good, however the first question is..what do I want to accomplish? This simple question becomes muddied by the new types of keyboards, stuff that does 'sort' of what Band in a Box does, that is arranges, sort of...but not quite.

I can say this, with the Ketron pat file, and the ketron hooked up by usb/midi you can't go wrong.

John Conley
Musica est vita