I wanna live a vibrant life, but I wanna die a boring death

Jack and Kate: I feel like they would make it about halfway. They're both competitive, fit, and fast. Butttt, Jack would never let Kate do roadblocks and that would start annoying her. Then they'd start arguing. Then, they'd crumble. I feel like they'd get tired and frustrated and spend like 4 hours doing a detour, ending up in last place.

Sawyer and Juliet: They could win. They balance each other out well. They're both athletic and clever. I see them making it to the finale for sure. Juliet would be patient and not panic when they were falling behind. Sawyer would be conning the other teams to get ahead. I don't see them fighting much, just engaging in some sarcastic banter.

Sun and Jin: They could also win. In the later seasons, I think they would. Jin would do any challenge that Sun didn't want to do. They would both be supportive of each other. Dare I say, later seasons Sun and Jin would not only win, but also have a great time. Early seasons Sun and Jin would not win (due to relationship conflict), but I do feel like they'd immerge with a stronger bond and understanding.

Desmond and Penny: They would be the third team in the finale. They both have like a million skills. And they work well together. I mean, Penny went looking for Desmond and FOUND HIM by herself. Desmond found Penny when he was stuck in a TIME LOOP. They have strong chances. I feel they would also have a great time just getting to be together.

Charlie and Claire: They would not do awesome. I feel like Charlie is extremely competitive and Claire is not. Charlie would get frustrated with her if she took too long or made a mistake. She would get frustrated with him if he started to get snappy. They would break up during the race. I can really see Claire withdrawing from the race, forcing Charlie to lose too.

Rose and Bernard: They would not make it very far. They're old. But, I think they'd make it through like 2 legs, because they do work well together. And Rose would always keep a positive attitude.

Libby and Hurley: I also don't see them making it very far. There's nothing objectively wrong with them, I just feel like their hearts wouldn't be in it. I also feel like they only work okay together. They might be too calm and too chill with no hustle.

I adore the way she is written in "Do No Harm". You can tell it was written by a woman. I adore the way she keeps trying to collect herself and get up. At every moment in which she starts to feel better, she immediately tries to regain her composure. A detail I noticed on my rewatch tonight also is that she immediately turns away and gets quieter every time someone new approaches. She tries to play it cool in front of Kate, you can see her trying to hold it together in the background when Jin shows up, and she physically turns her entire body away from Jin and Charlie later. We've seen this trait in her earlier, but I find that her uncomfortability with showing weakness is really emphasized in this episode.

I really see this in the miscommunication that happens with Kate, too. Kate seems to assume that Claire is just scared of giving birth without a doctor or a hospital. She must be scared of the classic stuff: pain, death, y'know. Wrong. Claire is petrified of the actual baby part. And even as they sit there together for like 4 hours, Kate witnessing some extremely personal moments for Claire, Claire never reveals why she's scared until the very end. It's like the last shred of dignity she wants to protect.

I also find it soooo compelling that this episode swerves the usual birth tropes of being scared of the pain and death. Those things are obviously scary, but I find it all the more powerful that those things are actually not at the front of Claire's mind. It makes her fear seem so much worse.