Just finished a marathon scenery check of all the 2020 airports I have from Simmarket. My first impressions of my 2020 payware airports in 2024 is actually very positive, especially with what we are seeing with aircraft.
Below is the Simmarket section of my add-on scenery for 2020 that I've installed in 2024 and checked. For the check I started the flight above each airport to scout how it blends in with the surrounding area and then when needed a low pass over detailed areas I wanted to look at. I think out of the whole lot, only KJAX installed itself into 2020 and had to be moved over to 2024. The rest went straight to 2024 when they had install apps.
These all passed with flying colors as far as blending in and looking great. What I didn't look for were any animated elements that each may have. I'll check that later when I make real flights into each of them.

Notes:
-I will probably switch the Pachilabs KJAX for the Fly-2-High version at some point. Pachilabs look really good but has the rectangular terminals, instead of the RL arched terminals.
-TTCP is one of the enhanced default 2024 airports so I checked which one looked better. As far as I can tell, 2024 used the airport from the Caribbean Pkg. They look exactly alike.
-TIST is actually much better in 2024 than it was in 2020. In 2020 there was a glaring mesh issue directly next to the terminal that left those buildings floating in the air. Drove me nuts every time I landed there. That's fixed in 2024.
-A perimeter elevation/mesh issue MDSD had in 2020 isn't there in 2024. Like TIST, this one looks better in the new sim.
Forest
Below is the Simmarket section of my add-on scenery for 2020 that I've installed in 2024 and checked. For the check I started the flight above each airport to scout how it blends in with the surrounding area and then when needed a low pass over detailed areas I wanted to look at. I think out of the whole lot, only KJAX installed itself into 2020 and had to be moved over to 2024. The rest went straight to 2024 when they had install apps.
These all passed with flying colors as far as blending in and looking great. What I didn't look for were any animated elements that each may have. I'll check that later when I make real flights into each of them.

Notes:
-I will probably switch the Pachilabs KJAX for the Fly-2-High version at some point. Pachilabs look really good but has the rectangular terminals, instead of the RL arched terminals.
-TTCP is one of the enhanced default 2024 airports so I checked which one looked better. As far as I can tell, 2024 used the airport from the Caribbean Pkg. They look exactly alike.
-TIST is actually much better in 2024 than it was in 2020. In 2020 there was a glaring mesh issue directly next to the terminal that left those buildings floating in the air. Drove me nuts every time I landed there. That's fixed in 2024.
-A perimeter elevation/mesh issue MDSD had in 2020 isn't there in 2024. Like TIST, this one looks better in the new sim.
Forest