A return to Penrod

I am wondering about Penrod's assertion that blogging encourages fluency in writing. Surveys, both informal and those cited by authors in journal articles I have read, indicate that students find it easier to write in electronic formats such as blogs compared to writing papers or essays. If people feel more comfortable writing in a particular medium, then, by its very definition, they are increasing one aspect of fluency -- their ease.
Yet, fluency also includes an accuracy component. Given the number of spelling errors that I have seen in blogs (my own and others), do blogs or other instant-post formats really increase the writing accuracy of students when compared with paper assignments (hand-written or word processed)? If I have the time, I would like to do a quick lit search on this question. I know that Penrod asserts that writers exert more care, as well as greater length, with blogs. But, who has actually looked at this data? Personally, I remember to "spell check" my papers more consistently than I spell check my blog posts or e-mail. I don't even know if the wiki site we are using and Facebook have a spell checker feature, so I certainly haven't taken the time to spell check my entries in those formats. 
Does anyone else have any knowledge of the research or have a reaction to Penrod's idea that blogs increase the care and presumably the accuracy of their writing? For instance, in this research article on the relationship between fluency and blogging that I found just by "googling" the keywords, the authors only examined # of words written. There does not seem to be a score for accuracy of writing.