Well I am. And here's why.
I am not really a keyboard player. Any one of my voice students can attest that the only way that we even SURVIVE lessons is by my drastic reduction of the accompaniment (which usually involves me using both hands to pull of playing the left hand part). When I auditioned/interviewed for the Master's program at BYU, they had me play a Bach chorale. The first one was in D-major, I failed it miserably! Then they gave me one in C-major, still failed it miserably!
So, I've worked LOTS to pull off playing the piano, at least to get the hymns to the level that I can play them. I pull that off mostly with LOTS of sustain pedal, and simplifying when necessary.
The Organ has no sustain pedal! Worse than that, it has LOTS of pedals that all make different sounds! I did play the organ for awhile at a Presbyterian Church in Salt Lake City, but that was way easy! I just had to play the melody in one hand and chords in the other, didn't even have to use the pedals!
So, tomorrow we'll see how it goes. I'm using pedals for the prelude, and the bass coupler for the Hymns. It should be fun, and hopefully it turns out okay!