Security of magic_quotes_gpc under PHP against SQL injection

I'm very curious as to what level of protection magic quotes provides against 
SQL injection attacks
(for MySQL, specifically) under PHP.  I have a rather lengthy app that relies 
upon magic_quotes_gpc
to sanitize database input, and information that goes straight back to the 
presentation layer from a
form is then stripslash'ed.

My question is, what are some ways around magic_quotes that I need to watch out 
for.. and as a
followup, if it's such a bad security idea, why was it included at all much 
less enabled by default
(this seems to smack of the register_globals problem, only to a lesser extent)?

I do understand that it would be a good idea to redo the entire app using 
mysql_real_escape, but in
this single-developer environment, I'd like to avoid doing a massive revamp 
unless it's of
penultimate importance to do so, because that cuts in to feature/usability 
development time.

Regards,
- Todd