I have been using PPG's 2021 for 17 years now. Both of my bikes are painted with it. One thing i love about it, is that its rock hard in a day or so depending on which hardener you use. My bikes take a lot of abuse, i am not easy on my stuff, and they hold up fine.
As for buffing, one time was out of town and did not buff the paint until 2 weeks after it was sprayed and it buffed out so easy.
Last year a customer from 12 years ago sent me his old tins as the bike had been wrecked. I had to paint a new set for him. I got to keep the old stuff and one of the tanks only had a small ding in it. I simply fired up my buffer and the paint looks like new.
I love this stuff and feel its the most painter friendly clear there is. Plus its hard like glass and looks like it.