Having used a Hammond B3 and a Leslie speaker in a band when a young man. It in my opinion, is impossible to get as good a sound, unless using that equipment. However, we have to adapt to what Yamaha has offered us, to use. It is possible to blend in their organ, and get a passable organ sound in a style/mix. Yes, I agree with you, about the sound.
I even bought an expensive stomp box supposed to give the Leslie sound, while it was a slight improvement, it was not worth the effort of incorporating it into my set-up. I also did the same with a wah-wah pedal, a slight improvement, but not worth all the work.
The Genos's job is to create as best an over-all sound as possible at a certain price point. But the beauty of a B3, live in real-time is that it's speakers are spinning spitting sound all over the room, and those sound waves are bouncing around, surrounding you in a sea of moving sound, harmonics etc. You can't recreate that with the sound coming from two sources (left, right speakers)..
My advice is to pick thru the organs, till you find, the one that best suits your needs. Since my favoring sound is a B3, Leslie rock'n'roll, Jimmy Smith sound. I don't find the organ packs highly desirable for my needs. But many will, if they play different organs, church music etc.