I agree with using only one space. Unfortunately, APA 6 has gone back to recommending two spaces for copy manuscripts to aid readability for readers who have to read a lot of draft text throughout the day (given that the APA manual is geared toward copy manuscripts).

To make matters worse, many organizations, schools, etc., misinterpret this recommendation and apply it to final manuscripts, which forces editors and formatters to ensure two spaces after end-of-sentence punctuation. So the find and replace above is quite helpful. Note that you should first find " ^w" and replace with " " without the quotes so that you are starting with a period with one space after each sentence (given that some users have entered 3 or more spaces after sentences), then run the replace all given by gmayor above.