First, I have to be honest, my professional musical training did not include organ performance (like many those who work as music director/ organist are , my professional background is classical piano performance) . Therefore, unless it is for special services, I usually minimize risk of adding organ pedal playing (not too used to use my feet in equal 'dexterity' degree of my hands). I either keep it extremely simple to use it as 'pedal point' (held down with minimal change of note/location, just to give solid bass line) or simply substitute similar register played by hand.
Long story short, there were a few funerals I had to play over the weekend and one service consisted of all Bach program for the musical pieces (Prelude, Offertory interlude, Postlude, etc) and most of them were "real" organ pieces. I tried them all both as organ pieces played only by hands and as full organ pieces involving the pedal. The musical verdict was pretty obvious - I had to play the full versions. I gave myself a challenge to master the excerpts of the listed pieces (in such services, we usually 'cut' and 'paste' parts of the requested pieces so that they all fit into service) in roughly 4 and half day.
What I noted was that it was actually fun to play the "real" organ pieces (not the hymns just to add certain solid pedal/bass line) and it was not that bad to adjust from hands-only to hands and feet coordination (with my notorious love of high heels). A bit ironic that heels actually helped a lot to balance on the pedal to enable the weight shift between the heel and the toe and vice versa to keep the legato line (mostly with right foot doing so, left foot did more of jumps from one location to the other - after all, I am a beginner using my feet as if they are additional 'hand' and I am guessing I am "right footed"). Obviously, the heel part of the shoes had to be a bit bulky so that it does not slip from the pedal. I am used to move pianistically (horizontally) with my hands at the keyboard and the feet only moving vertically for pedal change (feet do not have their position change since the piano pedals have totally different function from organ pedals). Yet movement-wise, it was not too difficult to manage the feet coordination, after watching some YouTube clips of organists performing similar (but not the same) pieces. I suppose visual learning of knowing "how to" helped a lot to learn my own movements. In fact, the hardest part was to designate the visual input (3 parts, not typical piano score of 2 parts, which is not really a problem - some piano pieces come with 2 or 4 parts though we only have 2 hands and we are used to read multiple layers/parts at a time) to actual movements by the specific limbs. I observed that I designate things fairly comfortably by judging from the register (or unless otherwise specified by the composer), which is usually the typical writing fashion you would see in piano scores with multiple layers. Due to such processing tendency, I kept mixing up the LH part with the pedal (feet) part due to their close/similar register ranges in first 2-3 days. That was the hardest to clarify and maintain the accuracy of actual playing (kept playing LH part by the feet and vice versa...). All went well for the performance/ services, though (phew!).
One thing I did not challenge myself enough this time was the change of sound within the piece. Organ playing comes with quasi-orchestration skills of selecting the sound combination for each section of the piece. You can pre-input it using specific pedals/ buttons/levers to do so - that is something I need to explore more for the truly organ pieces (I do this to certain extent but when I am only using my hands to avoid extra coordination). This requires more examination of sound colors and balance besides the additional coordination of pressing whatever for such function while I am already coordinating 2 hands and 2 feet! I think professionally trained organists are the most coordinated musicians of all and admire their fluid movements...
Though I do not intend to trade my primary instrument, I am intending to learn a few more "full" organ pieces to continue to give myself a healthy degree of coordination and musical challenge. It is true that when you have 'fun,' you learn well. I have discovered my new musical pastime (as it opposes to piano playing as a profession) and hope to continue experimenting and exploring with it further! For that, my music director work enables me to practice it with certain performance goals, which I find quite lucky :)