Regarding Derrick''s books/blog/, I can personally vouch for his integrity. I was pleased to sail with Derrick and Daveen for 4 days last summer. The information he provides is accurate and entertaining. His knowledge and experience as a worldwide skipper and sailor are amazing, having circumnavigated the entire continent of Australia, let alone the Great Loop.
He's the "real deal" and I hold our friendship in high regard.
John, I can speak for the transit Beth and I had last summer on the TSW, using the Garmin exclusively. We had no problem navigating the TSW and subsequently the Small Boat Channel in Georgian Bay using the Garmin. Also, I found the channels to be well marked and accurate. Also, there is plenty of boat traffic to follow and lend confidence in the transit. I, too, began the trip with a bit of trepidation, including the passage of locks but soon learned that this was a bit of over-kill on my part. Of course, not having reliable tools such as the Garmin, would be fool-hardy, as you so accurately point out.
Jeff