Interesting Miata NCAP crash test report
 

http://www.euroncap.com/tests/mazda_mx_5_2002/120.aspx

Doesn't look like it did too badly. Although, I believe the write up and 'score' is as it was when it was tested, i.e. a few years ago. Safety standards have come on a lot since then.
Note the comment referring to it being beneficial to have strong doors in a front impact. This seems to support my thinking about door bars deflecting front impact energy around the passenger cell. Door bars FTMFW.