I was looking at the quilt with DH before you posted your draft and we'd got to the point of 'seeing' the 9 patches and the 3 by 4 patches with the HSTs in them. So I'd say great minds think alike and would think this would be a much easier way of construction than the original maker describes - otherwise you'd be in scary Y seam territory!
The issues with layout are more to do with keeping the colours in the right places - I would make the blocks in sequence and use the design wall to keep them in order. I plan on trying to do the layout in EQ6 which will then help with the number of patches of each colour to be cut, fabric requirements, etc (although EQ always over estimates). I don't know when I'll get to it, but if I come up with anything useful, I'll post on here. :-D