SVN throws a big wrench in that, as when you make commits and updates in that fashion, and then want to update everything else in a checkout, it doesn't check the files that are there against the repository, it just says.. well you updated to this revision and I'm not going to second guess you.
What? I may not realy understand what you are saying but I recently learned the joy of version control using SVN. I must say it works quite well. It allows you to commit single files (or directories). You can then also update your other files. If you updated a file it checks it agianst the repository to make sure that the version you started with is the same version currently commited. I can't seem to get my head around what you are trying to say it does.