Gradients are a bit of a dark art! Your videos and experimentation are very useful indeed. When I first planned gradients on my layout, I got the woodlands scenics 2% and 4% grades. I was actually shocked at how little you could pull up a serious gradient - even with modern locos like the 181s or 071s. In the end, I all but removed gradients entirely, and kept things on the flat, tho I do plan a helix and storage level underneath the terminus, so am watching with interest! I've seen excellent reviews of the DCC Concepts powerbase too (their undertrack steel plate and magnet system)