I went to 2 tournaments.
Over a year ago, one small tournament in Oslo organized by board game shop. They didn't advertise it much. So although we have a big TM base here, almost no one I know was able to go that day. So I met there other players which was really nice. It was a small tournament, 3 games in 3 players, prelude + base + drafting of starting hand (5 + 5). Limit of 2,5 hours per game, then you finished the current generation and acted like the game is done. Because of limited time, we had to do 2 actions at the time (or 1 + pass). We got points based on the placement in the game. Second and third game, players with similar scoring played together. Most people who attended the tournament were used to play base/only some expansions. At that time, I was used to play only with everything (all expansions + promos + also fan made maps from BGG), so it was very different for me. But managed to get it to the final.
And now I attended Swedish championship organized by designers. 3 games in 4 players (2 tables 3 players), all played on new maps. First one only with prelude, second added venus, third added colonies. 4 best players went to final and played on Amazonis map, added also turmoil. Except the last game, there was limit of 2,5 hours. Then you finished current generation. If there was still some terraforming left, players had option to convert heat/plants and get TR, 1 by 1 going from starting player. Because of limited time, we were not allowed to play slow (1 actioning was ok, but long thinking during your turn was not allowed). What was surprising for me, is that many people had only very limited experience with expansions, even though the games were played with them. But they were overall good players, so managed to cope with that anyway. This time no final for me, ended in 1/3.
I have to say that those tournament were very nice. I prefer to play IRL and 3 games per day is something that I enjoyed very much.

It is also nice to meet other players and watch their player style.