Very cool! I'd be curious what you think of Modartt's recent attempts at physical models of organs and how they compare to more traditional sampler approaches.
Not OP, but I've worked on programming my own organ software before. I'd say physical modelling really cool tech, but the question is whether it makes a significant auditory difference.
The thing is organs are a lot easier to sample compared to something like a violin. I'm oversimplifying, but it's mainly just note on, note off, vs lots of articulations where physical modelling is more beneficial. (Yes, there's wind sag, and wind delay, and regulators, but most organs specifically have things to avoid those artifacts so they'd only show up on more niche organs imo.) I've had great success simulating tremulants by just using FM demodulation to reconstruct the pitch and volume effects from tremmed samples[1]. Release samples are also difficult to match with the current phase, but I was also able to mitigate that with a single bin DFT + crossfaded.
Another issue with physical modelling is it's decently CPU intensive, which is tricky when you have 700 simultaneous notes on bigger organs. So, it's definitely cool, but the question is whether it's significantly better than current sample-based technology. It could potentially reproduce some of the more strange interactions, but those interactions aren't necessarily wanted in the first place.
EDIT: one thing that is nice about physical modelling is it's a lot easier to voice (modify) a pipe to the sound one wants. I think with some special filtering (comb filter for even harmonic attenuation, shelf for augmenting the harmonic series trajectory) voicing could also be satisfactory with traditional sampling (hauptwerk does some of this, but I think I could make it even more flexible).
Physical modeling seems to work really well for guitar/bass amplifiers. The Fractal Audio products are all based around simulating the various components of an amp and the ways they interact with each other, often with very unexpected results. They've been pushing in this direction for quite awhile, but I think it is more promising than capture-based tech ultimately.
The modeling is so accurate that it ends up replicating even the unintended side effects of amps, such as ghost notes (false notes being produced due to the power supply). The tech note explains it better than I can: https://forum.fractalaudio.com/threads/ghost-notes.126903/
From my experience with the piano one, the "tweaking the sound" aspect is where I've got the most out of it. Even just for awareness. But yeah, the physical modelling approach is probably better suited to something like piano with all its interacting resonances (and the way a tuner can change things around on a real piano).
Not the one you asked, but I have both Hauptwerk and Organteq, and the former beats the latter on everything expect cost, memory usage, start-up time. Organteq sounds artificial, and its reverb doesn't make it any better. Ok, you can tweak a lot, but the ensemble sound is unconvincing, and the registration choices are too limited.
https://www.modartt.com/organteq_physical_modeling