Well, I can see two minor and one major issues already:
- my feed updates right away; feedburner introduces a lag of unknown size
- my feed includes the graphics (e.g. the mars item); feedburner, no doubt for bandwidth reasons, doesn't. But it doesn't tell you it's not there either…
- My feed was 100% of the post; feedburner truncates.
Maybe this won't be a very long experiment.