I guess what I've learned is how little I know. I want to take a tour to hear vintage horns- Mirrorphonic, a visit to David's, like that. But my "new" room has been great, it is much larger, and the combo of longer room, dual 15" servo subs, and stone bodied Koetsus has given my system some gravitas that it lacked.
I have heard the Mirrorphonics sound great at Munich, heard two sets of Bionors with Lamm and Kondo, and heard some Altecs, custom other horns with vintage drivers, etc. Vintage is to be respected. Drivers are great, crossovers and cabinets can be modded.
As to what I have learned:
1. If I could I would redo the search using the right records, i.e. listening points. However I understand this is not possible because you find records along the journey, so to find records you have to have spent a considerable time in your search already.
2. You mention big horns. And others mention big cones and panels. Yet, there is a lot of magic in small speakers, and simple set ups, that get out of the way of the recording better. They have less extensions and weight and all that, but by interacting less with the room and getting out of the way, suspension of disbelief can be better with the right records. Of course, if someone has big speakers that can get out of the way, that is ideal.
3. Price is way more complex than just the retail tag.
4. There are many sub hobbies. Cables, SS amps, SET amps, speakers, footers, analog, servers, dacs, etc. It is fine to indulge in different ones at different times. Personally for me, my hopefully final sub hobby is low watt amps. That will take a while though.
5. Understand your own purchase behavior. There is a big disconnect on how people listen, what they think, what they buy, how they justify. The sooner you understand what makes you tick and the people you talk to tick on these fronts, the better.
6. There is a big social element to this hobby. Whether meeting physically or virtually. So with 4, 5, and 6, when someone says I am just here for the music, he is either a. noob, b. lying to himself c. very advanced that he has been through all the subhobbies and extremely old.
7. Most people underdrive their speakers, some overdrive
8. 95% of the speakers I have heard are oversized for the room. I think it probably happens that an audiophile starts small, then keeps upgrading, then makes a jump to some big budget desirable he has lusted for as a small guy, and there he crosses the size line
9. Purchasing to announce on the forum is the biggest mistake, As the highs last for a few months then you need to make another big purchase to stay relevant
10. Don't lock yourself in upgrades. I would stay away from items where you stay locked in. It is just not worth it with the choices around
11. Videos are a great way to share knowledge.
12. On every other thing in life - food, work, sports, gym, diets, I have been able to share constructively. But in Audio it is almost impossible to be constructive without hurting the other person no matter how open he claims to be.