that's a nifty idea, to just swap out the @ symbol. it could certainly be effective, but it really comes down to how robust the individual spidering programs are.
it's possible that some spiders will still zero in on the .com element as an indicator that there is an email that can be harvested. there's really no way to know absolutely, since it's all about the spidering program's capabilities.
i make it a habit to fully encode the addresses on my sites in order to keep the evil-doer spammer spidering to an absolute minimum. that way, there's no .com, etc. elements that can raise a flag.