Tree Climbers International:
I would be willing to review and offer input. You mention you'll be covering DRT. There are two forms of doubled rope technique, the one that everyone commonly uses (2:1), and then there's the other, lesser known one where both ends of the rope are on the ground and you work the parallel lines in unison, with no movement of the rope at the crotch (true 1:1).
And why not SRT. Are you just sticking with the old-school techniques or are you going to be 'very comprehensive' as claimed and show three tree climbing _style_s instead of (possibly) just the one. No need to show caving setups or rock climbing rigs, or search and rescue stuff, just that what we do in the trees.
Will you cover new school methods like the use of hardware and 11 mm lines? I know this is a beginning and intermediate book, but it doesn't require an 'expert' to be able to ascend and descend three seperate rope _style_s using either friction hitches OR hardware. To me, that's the beginning of a 'textbook' on the subject.
That's my input so far. Let me know if more would be appreciated.

Tree Machine