Without wanting to be too techo-utopian, it would seem like some kind of automated system, that actively pulled in cooler outside air when available would outperform the manual intervention described in the article.

But generally, reversible air-con, in houses designed to be heated and cooled via heat pumps is a fine solution. Applying aftermarket air-con as a band aid is probably counterproductive, but that's not the only way to use air con.