So, if you moved to swomb.at, would you just redirect swombat.com to it? Is that a way people can have the best of both worlds?

1- you own the .com domain for branding, people understand it etc

2- your site isn't actually a .com

Would SEO be hurt by doing something like this?

I'm a huge believer in fighting link-rot as much as possible, so unless the US govt seized my domain for some reason, I would make sure all swombat.com links would still work.

Assuming the site had the same structure, you could easily 301 redirects to their .at equivalent.

SEO shouldn't be hurt (unless of course you are running the same site at both swomb.at and swombat.com), however with that said you won't get the seo boost that .com gives.

Another thought: swomb.at could be considered worse than say swombat.at as it is using the TLD to complete the word but I may be completely wrong in that case.