I use Compass with Blueprint for all projects these days.

When deploying on Heroku, the read-only filesystem has trouble with the conditional around the IE stylesheet - leading to something like this;

Errno::EROFS (Read-only file system - /disk1/home/slugs/.../mnt/public/stylesheets/compiled/ie.css - Heroku has a read-only filesystem.  See http://docs.heroku.com/constraints#read-only-filesystem)

I get around it by asking Compass / SASS to not bother trying to regenerate my sass/scss files in production:

in config/environments/production.rb:

Sass::Plugin.options[:never_update] = true