Yes. You will be at a signfiicant disadvantage

I am going to have to miss a few dinners, too. I think just make sure to explain the situation. They understand, and no, I don't think you will be at a significant disadvantage.

depends on the program- some programs require you to attend the dinner like Harvard, some say it is optional like Yale. so check in the email the wording for the dinner invitation, and whether they give you the option to RSVP. I would say most programs understand that sometimes we cant make it for dinner- especially that many flights are getting delayed in this season

Rationalize however you want but its better to attend one interview and the dinner than attend two interviews. Almost every program gives votes to residents or takes their input. If you don't attend dinner, you are much less likely to get support from them. Especially if you have a neutral interaction at the actual interview day

Strongly disagree with the previous statement. Current residents can veto you if you do something really inapporpriate but no program I've ever heard of gives them real weight in making the rank list beyond that veto. The residents might be able to subtly sway the attendings by saying good things about you but thats a small advantage at best. Go to more interviews and give yourself more ranks on your list. Maybe if you want to cancel a program you dont care about in order to make your top choice's dinner I could see doing that, but thats about it

Current resident here. I matched at a program despite missing dinner so it's not a deal breaker. I disagree with one of the comments --- many programs have residents interview or rank candidates. The chief residents usually have more weight.