In simple terms, power to weight ratio. I am a pretty big guy. In riding gear I am probably at 300 pounds. When I am on my 890 it probably feels to me, like a lighter person does on a 790. I don't care about super high top speed. I have other bikes for that. I just wanted a bike that would have a lot of usable power and be quick in the speed ranges where I use it the most, 0-100mph. That is why I bought the 890 over the 1290. The 1290 only really starts to be much quicker for me when above about 80-90 mph. In that range my Z H2 is quicker than the 1290 so no point considering it.
I think about 100 HP makes for about the right amount of power for the street for 90% of the riding I do. I don't care about top speed much any more as the laws are such that if I exercise that capability on the street I risk losing my license for a long time. Sure I can get away with a quick blast up to maybe 140-150 on my other bikes as I get there so quickly but I immediately have to let off as the risk becomes too great of a ticket.
The 2 most fun to bikes I have to ride on a daily basis both have about 100 HP and are more similar than I thought they would be; 890R and 2020 Africa Twin Adventure Sport DCT. They both are parallel twins, have very good midrange power, good suspension, comfortable ergos and pretty quick though not superbike quick/fast. And with both of them, I didn't like their smaller motored variants. When I rode the 790, I wanted more power. I had the 1000cc version of the Africa Twin and always felt I needed/wanted a bit more punch. I bought the 1100cc version and now it so much better for me and it is actually quicker than my 890 in a 0-60 sprint.
If someone can pick up a 790 cheap, then it could be a great value. When I bought my 890, there wasn't a huge difference in price and when I factored in all the things I would need to do to make it close to the 890, it would have ended up costing a lot more money and I would have a bike with basically no warranty. I learned a long time ago it is better to spend the extra money up front to buy what I want, than to buy something and do a lot of mods to get it where I want. The exception to that rule for me is if I can do an ECU reflash and unlock a lot more power on my turbo cars or how you can easily bump up the power on the H2 Kawis.
