Yes, Tarnagulla has great merit. It has areas of concentrated detail separated by areas of contour blandness, but still dotted with point features. Also in its favour is that its fast and open.
Julie and I did a serious wander in Lightning Ridge, finding many large boulders, but also many green areas and lots of contours. Its not just that you have to go cross country. You have to go uphill, steeply. Better than Mt Hickey, but that isn't saying much. If there was a flatter area with those boulders maybe. Here is proof of our explorations. https://photos.app.goo.gl/Yz1vFBMNJqTGcda96
And I had the same experience as Blair in wandering through Reef Hills. Must have wandered in the wrong place. If there was lidar available for the area I would have known where to look. Looking at the Mapshare 10 metre contours, I am guessing I should have gone east rather than south. At least there are contours in the east, and it doesn't look like it has the problems of lightning ridge. Hence the need for a tour.