Hiro11

You can get a Di2 bike for about the same price as mechanical DA. I went with hydro Di2 for my bike this year.

Since high school, I've always paid the (small) premium for Ultegra over 105. I have no idea if there's any real difference between the two groups, I suspect not. Still, components last a long time if you take care of them (and don't crash), amortizing the small extra cost of Ultegra over the life of the components make this incremental cost essentially meaningless. On the other hand, Dura-Ace's almost literal DOUBLING of Ultegra cost for very marginal differences has always been hard for me to logically justify. Dura-Ace is for people who want Dura-Ace, if you catch my drift. I've only bought Dura Ace once in my life and that was all the way back in the 8-speed 7402 era.

I've always gone by the rule of thumb to only ride bikes I can afford to crash and utterly destroy with impunity. As I've gotten older and made more money, the bikes that fit that description have gone up in price.

BTW, I agree that the 7800/6600 was likely the pinnacle of "old school" Shimano. Impeccable performance, unbeatable durability, classic looks and easy to work on. I still have a road bike with 6600, I don't think that stuff is ever going to die. I replaced the cables, brake pads, chainrings, chain and cassette just for the hell of it this summer. That bike is good for another 15 years.