Thank you all for the information, some really good stuff.
See the attached screen shot with skeletal framing for the mountain. After the 'Y' on the top half, the right branch has a down grade, the left branch has an up grade. So what ever grade I end up with, it would be like having double the %, 3% = 6% and 2.5% =5%. Trying to capitalize on my space restrictions. With my space limitations, don't know about 'Scale' consists. I'm thinking this will be mostly for smaller Legacy units, semi-scale, 'standard' scale with some LC+ 2.0.
I'll take the advise of as little as necessary grade. Thinking the upper reversing loop will have a winter scene, think"Glacier Line".