No real opinion on pros and cons, although it might be a smart move to have your SIP address the same as your email address. On the other hand, maybe a phone number would be better… Hmm, i see your problem!
However, i would question the wisdom of taking this approach to telephony - if you’re intending to allow the whole world to connect to your asterisk server to make calls, that is. It’s a serious security issue.
As far as how to do it goes, i answered that question for someone else yesterday… Here:
The plan is to assign a sip address to a user such that he/she will be able
to receive sip calls. Given that there will be spam or irritating calls,
but the idea is that the user will be reachable through his/her sip address.
On the sip address to use, where there be an issue for a SIP phone to call URI-based SIP address?