I use foundation at work. We have the rule that "make the site look fine in IE7", where it has to work but it doesn't have to be perfect.

You can use foundation 3.1 with the htc boxing fix [1] that fixes the grid problems with IE7.

I love use foundation over BS, since BS (to me atleast) is more of a UI decision, where you build your site from scratch with foundation).

[1] https://github.com/Schepp/box-sizing-polyfill