I feel your pain on both points! I don't start posts much anymore as so many people pick up on one aspect and start off on a tangent and the actual question is ignored. This lead to others responding to their topic and the OP is left scratching their head lol
Now to your post. I had the exact same experience when I started my Transparent journey last year. I emailed their support email asking for comparisons across both generation and level. They have 10 levels that almost exactly doubles in price at each jump. I think it is fair that anyone considering or currently using would wonder how Reference MM2 compares to Ultra Gen 5, for example. Ian politely told me they simply do not ever attempt this. All he would say is that each level up is an improvement and separately each generation is an improvement.
I spoke with a dealer and his advice to me was that Gen 5 was a significant upgrade across the board for Transparent. He suggested I not consider any level below that if I was starting with Transparent. He also said that Gen 6 was not impressive and worth the extra expense unless you were in the top 3 or 4 levels.
I believe Transparent could be more open with their clients and offer similar advice. I am also an Audio Research fan and have similar conversations with them where they were very open about cross-generation and level comparisons.
I suppose at the end of the day you/we never know until we pull the trigger and just try something. FWIW, I ended up going with a mix of Gen 5 Super and Ultra simply based on how used opportunities presented themselves when I was buying.
Good luck.